High purity lithium and associated processes

ABSTRACT

High purity lithium and associated products are provided. In a general embodiment, the present disclosure provides a lithium metal product in which the lithium metal is obtained using a selective lithium ion conducting layer. The selective lithium ion conducting layer includes an active metal ion conducting glass or glass ceramic that conducts only lithium ions. The present lithium metal products produced using a selective lithium ion conducting layer advantageously provide for improved lithium purity when compared to commercial lithium metal. Pursuant to the present disclosure, lithium metal having a purity of at least 99.96 weight percent on a metals basis can be obtained.

PRIORITY CLAIM

This application is a divisional application of U.S. patent applicationSer. No. 15/160,013, filed on May 20, 2016, which claims the benefit ofU.S. Provisional Patent Application No. 62/168,770, filed May 30, 2015,U.S. Provisional Patent Application No. 62/183,300, filed Jun. 23, 2015,and U.S. Provisional Patent Application No. 62/284,812, filed Oct. 9,2015, the disclosures of each of which are incorporated into thisspecification by reference in its entirety.

FIELD OF TECHNOLOGY

The present disclosure generally relates to high purity lithium andassociated products. More specifically, for example, the presentdisclosure relates to highly purified lithium metal produced using aroom temperature electrolytic process facilitated by a cell consistingof electrolytes and a membrane that selectively conducts only lithiumions to generate highly purified lithium and products incorporating thehighly purified lithium metal. In an embodiment, the disclosed lithiummetal has a purity of greater than 99.96 weight percent on a metalsbasis. Additionally the present disclosure also relates to continuousprocesses for obtaining lithium metal and cells for carrying out theprocess.

BACKGROUND

Lithium is a soft, silver-white metal belonging to the alkali metalgroup of chemical elements. Lithium is present in over fifty compoundsand has two stable isotopes, Lithium-6 and Lithium-7. It is the lightestmetal and the least dense solid element. Lithium is highly reactive andflammable, though it is the least reactive of the alkali metals. Sincelithium only has a single valence electron that is easily given up toform a cation, it is a good conductor of heat and electricity. Lithiumalso has the highest electrochemical potential of all metals.

Because of its high reactivity, lithium does not occur freely in nature.Instead, lithium only appears naturally in compositions, usually ionicin nature, such as lithium carbonate. Therefore, lithium metal can beobtained only by extraction of lithium from compounds containinglithium.

The two most common ways of obtaining lithium are currently throughextraction of lithium present in either spodumene or brine, producingcarbonate. Lithium is then obtained from the lithium carbonate in twophases: (1) conversion of lithium carbonate into lithium chloride, and(2) electrolysis of lithium chloride using a high-temperature moltensalt such as LiCl.

To convert lithium carbonate to lithium chloride, the lithium carbonateis heated and mixed with hydrochloric acid (typically 31% HCl) in anagitated reactor to generate lithium chloride, carbon dioxide and wateras shown below:

Li₂CO₃(s)+2HCl(aq)→2LiCl(aq)+H₂O(aq)+CO₂(g)

The formed carbon dioxide is vented from the reactant solution. A smallamount of barium chloride can be added to precipitate any sulfate. Afterfiltering, the solution is evaporated to a saleable 40% LiCl liquidproduct. Potassium chloride can be added to provide a dry lithiumchloride-potassium chloride (45% LiCl; 55% KCl) of decreased meltingpoint (614° C. to approximately 420° C.). Then the lithiumchloride-potassium chloride (45% LiCl; 55% KCl) in a molten pure and drystate can be utilized to produce lithium metal in a steel reaction cellusing electrolysis as shown in the reactions below:

Cathode: Li⁺ +e ⁻→Li metal

Anode: Cl⁻→½Cl₂ +e ⁻

Total: 2LiCl→2Li+Cl₂

A conventional steel reaction cell has an exterior ceramic insulationand a steel rod on the bottom as a cathode. The anode is constructed ofgraphite, which slowly sloughs-off during processing. When the cell isheated, lithium metal accumulates at the surface of the cell wall and isthen poured into ingots. Chlorine gas generated by the reaction isrouted away. Typically, the electrolysis process is operated with a cellvoltage from 6.7 V to 7.5 V, and the typical cell current is in therange of about 30 kA to 60 kA. The electrolytic processing consumesabout 30 kWh to 35 kWh of electricity energy and about 6.2 to about 6.4kg LiCl to produce one kilogram lithium metal with about 20% to 40%energy efficiency. Improvements to the molten salt electrolysis processhave involved the selection of different types of electrolytic moltensalts that allow for a decrease in operating temperatures.

For example, U.S. Pat. No. 4,156,635 to Cooper et al. describes anelectrolytic process for the production of lithium using alithium-amalgam electrode. The lithium is recovered from its moltenamalgam using a fused-salt molten electrolyte consisting of a mixture ofat least two alkali metal halides. The metal halides may include lithiumiodide, lithium chloride, potassium iodide, and potassium chloride. U.S.Pat. No. 4,156,635 teaches that the lithium amalgam is produced byelectrolysis of an aqueous solution of a lithium salt such as lithiumhydroxide in the present of a mercury cathode. The lithium amalgam isthen circulated between an aqueous cell containing the lithium saltsolution and a fused-salt cell containing the molten electrolyte, andthe lithium amalgam serves as a bipolar electrode.

Another low temperature technology involves electrolysis of brine toform chlorine at an anode and sodium hydroxide or potassium hydroxidevia a series of cathode reactions. The formation of either of thesehydroxides can involve the reduction of Li⁺ to metal at a liquid mercurycathode, followed by reaction of the formed mercury amalgam with water.The process operates near room temperature with a lower voltage thanrequired for the molten salt system.

U.S. Pat. No. 8,715,482 to Amendola et al. provides a system and processfor producing lithium without a mercury electrode. The liquid metalalloy electrode system of U.S. Pat. No. 8,715,482 includes: anelectrolytic cell comprising a liquid metal cathode and an aqueoussolution wherein the aqueous solution containing lithium ion and atleast an anion selected from sulfate, trifluoromethane sulfonate,fluorosulfonate, trifluoroborate, trifluoroacetate, trifluorosilicateand kinetically hindered acid anions, and wherein the lithium ion isproduced from lithium carbonate. A heating system maintains temperatureof the cell and liquid metal circulating systems higher than the meltingpoint of the liquid metal cathode but lower than the boiling point ofthe aqueous solution. The reduced lithium from the electrolytic cell isextracted from the liquid metal cathode using a suitable extractionsolution and a distillation system for isolating the lithium metal. Thissystem is solid at room temperature and is less toxic than previoussystems.

U.S. Pat. No. 6,770,187 to Putter et al. discloses another process thatovercomes some of the high energy consumption and high temperaturerequirements of prior art processes. The process enables recycling ofalkali metals from aqueous alkali metal waste, in particular, lithiumfrom aqueous lithium waste. U.S. Pat. No. 6,770,187 provides anelectrolytic cell comprising: an anode compartment which comprises anaqueous solution of at least one alkali metal salt, a cathodecompartment, and an ion conducting solid composite that separates theanode compartment and the cathode compartment from one another, whereinthat part of the surface of the solid electrolyte composite that is incontact with the anode compartment and/or that part of the surface ofthe solid electrolyte that is in contact with the cathode compartmenthas/have at least one further ion-conducting layer. The electrolyte usedin U.S. Pat. No. 6,770,187 is water or water with organic solvent.

Lithium metal readily reacts with water to form hydrogen gas and lithiumhydroxide. Because of its reactivity, lithium metal, once extracted froma lithium compound, is usually stored under cover of a hydrocarbon,often petroleum jelly. Though the heavier alkali metals can be stored inmore dense substances, such as mineral oil, lithium metal is not denseenough to be fully submerged in these liquids. In moist air, lithiummetal rapidly tarnishes to form a black coating of lithium hydroxide(LiOH and LiOH.H₂O), lithium nitride (LiN) and lithium carbonate(Li₂CO₃).

Because of lithium's high electrochemical potential, it is an importantcomponent of electrolytes and electrodes in batteries. For example,lithium metal is commonly used as an anode material in a lithium primarybattery. Lithium metal is currently used as an anode material in tworechargeable batteries: a lithium sulfur battery developed by Sion PowerCompany and a lithium metal polymer battery used by the Bolloré Group.However, the lithium sulfur battery mentioned above requires aprotective cover on the anode, and the lithium metal polymer batterytechnology utilizes a low capacity cell system specifically integratedinto an electric vehicle. Mass adaptation of lithium metal anodes inrechargeable batteries has not yet been realized due to problems withdendrite formation.

Lithium metal anodes are particularly desirable for use in batteries,since batteries using a lithium metal anode have much higher energydensities than batteries using graphite or other conventionalnon-lithium anode materials. Lithium metal anodes have the highestspecific capacity value of 3.86 Ah/g and energy density of 1470 Wh/Kg.

However, lithium metal produced by conventional lithium producingprocesses contains impurities that undesirably cause dendrite formationwhen the lithium metal is used as an anode in a rechargeable battery.The conventional process produces lithium foils with surface defects andcracks which serve as nucleation sites for dendrite growth For example,during charge and discharge cycling of the battery, impurities in thelithium metal cause lithium crystals (i.e., “dendrites”) to emerge fromthe surface of the anode and spread across the electrolyte. In lithiumpolymer systems, dendrites begin forming at the electrode underneath thepolymer/electrode interface prior to coming into contact with theelectrolyte. In the same system, dendrites have also been observed onthe uncycled lithium anode. Dendrite formation causes the battery toshort-circuit, thereby increasing the temperature of the battery topotentially unsafe levels, resulting in thermal runaway or even death.Therefore, higher-purity lithium metal with a stable, uniform solidelectrolyte interphase (SEI) layer that does not contain the impuritiesresulting from conventional lithium producing processes is desirable,and would result in a two-fold reduction of dendrite suppressingefforts, firstly by eliminating nucleation sites, and secondly byeliminating side reactions due to impurities.

Metallic lithium can also be used as a flux for welding or soldering topromote fusing of metals to eliminate oxide formation by absorbingimpurities. Its fusing quality is important as a flux for producingceramics, enamels and glass. Metallic lithium is also used in themetallurgical industry to form alloys containing lithium. High puritylithium metal is desirable in forming alloys to reduce the overallimpurity level in the alloys. High purity lithium metal and alloyscontaining such high purity metal are also desirable as an improvementin currently available primary lithium batteries. Furthermore,increasing the concentration of lithium metal in an alloy, such as alithium aluminum alloy, would result in an increased performance andlifespan for primary lithium batteries.

Lithium metal may also be used to make certain lithium compounds. Forexample, lithium oxide may be used as a flux for processing silica toglazes of low coefficients of thermal expansion, lithium carbonate(Li₂CO₃) may be used as a component in ovenware, and lithium hydroxide(LiOH) may be used as a strong base that can be heated with a fat toproduce a lithium stearate soap. Lithium hydroxide monohydrate may beused as feedstock to produce a cathode material used in cylindricalcells, such as the Panasonic 18650 rechargeable lithium-ion battery.Notably, nickel cobalt aluminum (NCA) cathodes used in the cylindricalcells may require a high-purity LiOH. The cylindrical cells may be usedin a battery pack. Lithium soap can be used to thicken oils and in themanufacture of lubricating greases. Lithium metal may also be used toform lithium fluoride. Due to its ultraviolet (“UV”) transmission,lithium fluoride is used as a material in special UV optics. Lithiumcompounds are used in a wide variety of lithium battery electrolytes,for example LiPF₆, a common Lithium-ion battery electrolyte. Lithiumsalts such as lithium carbonate, lithium citrate and lithium orotate arealso used in the pharmaceutical industry as mood stabilizers to treatpsychiatric disorders such as depression and bipolar disorder. Highpurity lithium is desirable when making these lithium compounds in orderto reduce the overall impurity level in the resulting compounds.

SUMMARY

There is a need for high purity lithium metal that does not contain theimpurities typically present in lithium metal produced by conventionalprocesses. Previous lithium producing systems have involved substantialcapital and operating costs, and use and release noxious materialsincluding mercury. There is therefore also a need for a direct andimproved electrolysis process that requires reduced capital andoperating costs in a system that effectively provides direct productionof lithium metal.

In one non-limiting aspect, the present disclosure relates to highpurity lithium metal that does not contain the impurities associatedwith conventional lithium producing processes. In an embodiment, thepresent disclosure provides a lithium metal product obtained using aselective lithium ion conducting layer. The lithium metal productincludes a lithium metal having a purity of greater than 99.96 weightpercent on a metals basis. The high purity lithium metal can be free ofmercury and other nonconductive impurities that are present in lithiumproduced by conventional processes.

In an embodiment, the lithium metal is free of any metal impurities.

In an embodiment, the lithium metal has a purity of 100% weight withouta solid electrolyte interphase (SEI) layer.

In an embodiment, the lithium metal has a stable uniform solidelectrolyte interphase (SEI) layer with a skin depth less than 4 μmthick which can be customized for specific battery technologies bymodifying the electrolyte.

In an embodiment, the lithium metal films are smooth, dendrite free, anduniform under scanning electron microscopy (SEM) images at 0.4 μm.

In an embodiment, the selective lithium ion conducting layer comprisesan active metal ion conducting glass, glass-ceramic, or aglass-ceramic-polymer. In such an embodiment, the selective lithium ionconducting layer may include a lithium ion conductive barrier film.

In an embodiment, the lithium metal is coated onto a strip of materialin a continuous strip coating process. The lithium-coated strip may becontinuously fed into a system for producing a lithium compound such aslithium hydroxide.

In an embodiment, the lithium metal may be processed with deionizedwater to form lithium hydroxide and hydrogen, or lithium hydroxidemonohydrate.

In an embodiment, the lithium metal is obtained by extracting lithiummetal from a lithium salt using the selective ion conducting layer.

In an embodiment, a lithium metal electrode is provided. The lithiummetal electrode includes lithium metal that is obtained by extractinglithium metal from a lithium salt using the selective ion conductinglayer.

In an embodiment, a battery is provided and includes a cathode, an anodeand an electrolyte. The anode comprises lithium metal that is obtainedusing a selective lithium ion conducting layer.

In an embodiment, a lithium metal compound is provided. The lithiummetal compound includes lithium metal that is obtained using a selectivelithium ion conducting layer.

In an embodiment, a lithium metal alloy is provided. The lithium metalalloy includes lithium metal that is obtained using a selective lithiumion conducting layer.

In an embodiment, the present disclosure provides a process of producinglithium hydroxide. The process includes extracting lithium metal from alithium salt using a selective lithium ion conducting layer. The lithiummetal is processed with deionized water to form lithium hydroxide andlithium hydroxide monohydrate.

In an embodiment, the present disclosure provides a lithium producingcell that includes a cell body, a sulfuric acid solution within the cellbody, an anode within the cell body, an opposing and adjustable cathodemoveable within the cell body, a catholyte on the cathode side of thecell, and a conductive glass-ceramic composite layer intercalatedbetween the cathode and the electrolyte aqueous solution. The sulfuricacid solution contains lithium ion and an anion. The cell can include aninsertion/retraction module connected to the cathode to adjustablycontrol the cathode.

In an embodiment, the present disclosure provides a process for reducingimpurities in lithium. The process includes providing a lithium ionsource in a sulfuric acid solvent wherein lithium anion is dissolved inthe solvent to form a lithium feed solution. An anode is provided incontact with the solution. A composite layer is provided transecting anaxis of the cell body, the composite layer, comprising a lithium ionglass-ceramic. An adjustable cathode is moveable within the cell bodycathode to a position apart from composite layer contact and suitablefor electrolysis of lithium. A catholyte is provided on the cathode sideof an electrolytic cell. An ionizing electric current is provided to theelectrolytic cell, thereby producing lithium metal at the cathode.

In an embodiment, the present disclosure provides a process forseparating Lithium-6 and Lithium-7 isotopes from lithium metal. Theprocess includes providing an electrolytic cell comprising an organicaqueous solution. A nonaqueous electrolyte and a selective lithium ionconducting membrane are provided. The Lithium-6 and Lithium-7 isotopesin the lithium metal are caused to pass through the membrane atdifferent velocities. At least one of the Lithium-6 and Lithium-7isotopes are captured.

In an embodiment, enriched Lithium-6 and Lithium-7 isotopes areprovided. The enriched isotopes are obtained using an electrolytic cellcomprising an organic aqueous solution, a nonaqueous electrolyte and aselective lithium ion conducting membrane to separate the lithiumisotopes.

In an embodiment, a lithium metal containing product is provided. Thelithium metal comprises, in parts per million by weight: less than 0.6silver (Ag), less than 2 aluminum (Al), less than 0.2 arsenic (As), lessthan 0.1 gold (Au), less than 0.4 boron (B), less than 0.4 barium (Ba),less than 0.5 beryllium (Be), less than 0.1 bismuth (Bi), less than 4calcium (Ca), less than 0.5 cadmium (Cd), less than 0.4 cerium (Ce),less than 0.4 cobalt (Co), less than 0.4 chromium (Cr), less than 0.4cesium (Cs), less than 0.4 copper (Cu), less than 0.4 dysprosium (Dy),less than 0.4 erbium (Er), less than 0.5 europium (Eu), less than 0.7iron (Fe), less than 0.4 gallium (Ga), less than 0.4 gadolinium (Gd),less than 0.3 germanium (Ge), less than 0.2 hafnium (Hf), less than 0.3mercury (Hg), less than 0.3 holmium (Ho), less than 0.5 indium (In),less than 0.2 iridium (Ir), less than 0.5 potassium (K), less than 0.4lanthanum (La), less than 0.1 lutetium (Lu), less than 5 magnesium (Mg),less than 0.3 manganese (Mn), less than 0.4 molybdenum (Mo), less than0.3 niobium (Nb), less than 0.4 neodymium (Nd), less than 0.9 nickel(Ni), less than 0.4 osmium (Os), less than 10 phosphorus (P), less than0.1 lead (Pb), less than 0.5 palladium (Pd), less than 0.4 praseodymium(Pr), less than 0.2 platinum (Pt), less than 0.4 rubidium (Rb), lessthan 0.1 rhenium (Re), less than 0.3 rhodium (Rh), less than 0.4ruthenium (Ru), less than 13 sodium (Na), less than 19 sulfur (S), lessthan 0.3 antimony (Sb), less than 0.5 scandium (Sc), less than 1selenium (Se), less than 69 silicon (Si), less than 0.5 samarium (Sm),less than 0.7 tin (Sn), less than 0.5 strontium (Sr), less than 0.1tantalum (Ta), less than 0.3 terbium (Tb), less than 0.4 tellurium (Te),less than 0.1 thorium (Th), less than 0.4 titanium (Ti), less than 0.1thallium (Tl), less than 0.2 thulium (Tm), less than 0.1 uranium (U),less than 0.5 vanadium (V), less than 0.2 tungsten (W), less than 0.4yttrium (Y), less than 0.2 ytterbium (Yb), less than 1 zinc (Zn), andless than 0.3 zirconium (Zr). Thus, the total impurities in the lithiummetal are less than 0.002 weight percent.

In an embodiment, the disclosed lithium metal has a purity of greaterthan 99.998 weight percent on a metals basis. In an embodiment, the highpurity lithium metal has no impurities above the minimum detectablelimit of the inductively coupled plasma mass spectrometry (ICP-MS)method. In an embodiment, the high purity lithium metal has noimpurities.

An advantage of the present disclosure is to provide a lithium metalproduct having an improved lithium metal purity. By using a selectivelithium ion conducting membrane to extract lithium metal from a lithiumsalt, the impurities present in conventional lithium producing processesare not passed to the final lithium metal product.

Another advantage of the present disclosure is to provide an electrodecontaining a lithium metal anode with an improved purity of lithium anda battery containing such an electrode. By providing a lithium metalanode having a high purity, the concentration of the active material isincreased resulting in higher capacity, longer cycle life and energydensity. The anode can be used in batteries without causing orcontributing to dendrite formation, therefore mitigating catastrophicconsequences.

Still another advantage of the present disclosure is to provide lithiumalloys and lithium compounds containing a lithium metal having animproved purity. By providing a lithium metal compound or alloy having ahigher purity, the final alloy or compound can desirably have animproved overall purity.

Another advantage of the present invention is to provide a process thatconsumes less energy. Traditional electrolytic processing consumes about30 kWh to 35 kWh of electrical energy to produce one kilogram lithiummetal with about 20% to 40% energy efficiency. The presently disclosedprocess uses only 8 kWh of electrical energy to produce one kilogramlithium metal with 90% to 100% efficiency.

Another advantage of the present invention is to provide a number ofproducts that can contain the lithium metal of the present disclosure.By way of an example, the products include a camera, a camcorder, acomputer, a cellular phone, a personal digital assistant, a clock, awatch, a car key, a sensor, a remote control, an audio device, anaudiovisual device, an oceanographic device, a capacitor, ametacapacitor, a supercapacitor, an automobile, an airplane, a drone, aspacecraft, a satellite, an implantable medical device, a consumerproduct, a primary battery, and a rechargeable battery.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic elevation view of a lithium producing cellstructure used to produce a high purity lithium metal product in anembodiment of the present disclosure.

FIG. 2 is an enlarged partial view of the lithium producing cellstructure of FIG. 1.

FIG. 3A is a schematic elevation view of a lithium producing cell usedto produce a high purity lithium metal product in another embodiment ofthe present disclosure.

FIG. 3B is a side view of the lithium producing cell of FIG. 3A.

FIG. 3C is a section view taken along E-E of FIG. 3A.

FIG. 3D is an enlarged partial view of the lithium producing cell ofFIG. 3C.

FIG. 3E is a rear perspective view of the lithium producing cell of FIG.3A.

FIG. 4 shows a schematic exploded view of a lithium producing cell ofExample 1.

FIG. 5 shows schematic views of insertion/retraction module-adaptedcells.

FIG. 6 shows a schematic view of a strip coating system according to anembodiment of the present disclosure.

FIG. 7 shows a schematic view of a continuous strip coating systemaccording to another embodiment of the present disclosure.

FIG. 8 shows a small-scale strip coating system according to anotherembodiment of the present disclosure.

FIG. 9 is a section view of a lithium production cell according toanother embodiment of the present disclosure.

FIG. 10A is a schematic elevation view of a lithium producing cellaccording to another embodiment of the present disclosure.

FIG. 10B is a section view of the lithium producing cell of FIG. 10A.

FIG. 11A shows a series of micrographs of a lithium film according tothe present disclosure (99.998% metals basis; 100 μm thickness) on Cu ascompared to the prior art lithium foil.

FIG. 11B shows a series of micrographs of surface views and edge viewsof a lithium film according to the present disclosure (99.998% metalsbasis; 100 μm thickness) on Cu.

FIG. 12 shows two optical micrographs of lithium films according to thepresent disclosure on copper samples.

DETAILED DESCRIPTION

The present disclosure generally relates to high purity lithium andassociated products. Additionally the present disclosure also relates tocontinuous processes for obtaining lithium metal and cells for carryingout the process.

According to certain non-limiting embodiments, the present disclosureprovides an extractable/insertable cathode separated from lithium ionrich solution by a selectively permeable barrier composite. Thecomposite comprises a lithium ion conductive glass-ceramic (LiC-GC)layer. The lithium ion conductive glass-ceramic (LiC-GC) compositeallows for direct production of lithium metal from solution and directdeposition of lithium metal onto a clean cathode, without need for anadditional extraction process.

According to certain non-limiting embodiments, the present disclosureprovides a system including an electrolyte feed system that provides alithium ion rich electrolyte to the electrolytic cell, and anelectrolytic cell to move lithium metal from a water-based lithium ionsolution through the lithium ion conductive glass-ceramic (LiC-GC)membrane.

According to certain non-limiting embodiments, the present disclosureprovides a method to remove the lithium metal from the cell and thencontinue production with that cell, and a method to package lithiummetal. The method can be part of a continuous lithium metal productionprocess or as a batch process.

According to certain non-limiting embodiments, the present disclosureprovides a high purity lithium metal that is obtained using a selectivelithium ion conducting layer and products containing the high puritylithium metal. The high purity lithium metal can be extracted fromlithium carbonate or other naturally occurring sources of lithium. Thelithium metal has high purity on a metals basis due to the selectiveconduction of lithium ions across the lithium ion conducting layer. Thehigh purity lithium metal may be used to produce lithium hydroxide thenevaporated to produce lithium hydroxide monohydrate.

A high purity lithium metal according to an embodiment may be producedusing a cell as shown in FIGS. 1 and 2. In FIGS. 1 and 2, theelectrolytic cell 10 includes an upper section 12 and lower section 14.The cathode 16 transposes an axis of cell 10, advancing as anelectrolysis reaction takes place in electrolyte 18 above the cathode16, through a lithium ion conductive glass-ceramic-barrier film(LiC-GC-BF) composite layer 28. When potential is applied to the system,lithium metal builds up on the moving cathode 16 below the compositelayer 28. Anode 20 is provided in the cell upper section 12. The cellsection 12 above the cathode 10 is loaded with electrolyte 18 via inlet22, electrolysis proceeds and spent electrolyte is discharged via outlet24. The cathode 16 is in contact with the electrolyte 18 through thecomposite layer 28 intercalated between the cathode 16 and electrolyte18.

The composite layer 28 comprises a lithium ion conductive glass-ceramic(LiC-GC) layer 30 adjacent the electrolyte 18 and a lithium ionconductive barrier film (Li—BF) 32 interposed between the ceramic layer30 and cathode 16. The barrier layer 32 and glass-ceramic layer 30,together, composite 28, isolates forming lithium at cathode 16 fromelectrolyte 18. Shaft 26 advances the cathode 16 and composite 28 aslithium metal is formed and deposited through the composite layer 28onto the advancing cathode 16. The lithium metal produced at the solidcathode 16 can be drawn off as a pure metallic phase to form a highpurity lithium product.

Alternatively, in a non-limiting embodiment, the lithium metal producedat the cathode 16 allows for flexible deposition onto a myriad ofdifferent substrates that can easily be integrated into some batterymanufacturers' production processes, thereby streamlining the processes.Examples include a copper foil, a graphite coated copper foil(capacitor), (Li₇La₃Zr₂O₂ (LLZO) Garnet), onto Cu by atomic layerdeposition (ALD), onto a 3D current collector/substrate, a grooved pieceof Cu or appropriate substrate, or a rotating cathode can deposit micronsized rods of lithium with a stable uniform solid electrolyte interphase(SEI) layer onto the substrates used in microbatteries in a continuoussystem.

Alternatively, the lithium metal produced at the cathode 16 may be usedto produce lithiated substrates, such as a carbon anode lithiated withhigh purity lithium rather than deposited lithium.

Alternatively, the lithium metal produced at the cathode 16 may bedirectly coated onto a strip of material in a continuous strip coatingprocess. The lithium-coated strip may then be continuously fed into asystem for producing a lithium compound such as lithium hydroxidemonohydrate. Specifically, the high purity lithium metal may be mixedwith deionized water to form lithium hydroxide and hydrogen according tothe following reaction:

2Li+2H₂O→2LiOH+H₂

The hydrogen produced in this lithium hydroxide formation process may bevented off, burned off or stored. For example, the hydrogen may beburned off in air to form water, or simply vented to the atmospherewhere it will combine with oxygen to form water vapor. Alternatively,the hydrogen may be captured in capsules or cartridges. The capsules orcartridges containing hydrogen may be used as rechargeable cartridges ina fuel cell battery for consumer electronics.

Alternatively, to produce lithium hydroxide monohydrate, the cell can bemodified to be used as a two (or three) chamber electrolyzer. Theaqueous solution remains Li₂CO₃ and sulfuric acid by a simple metathesisreaction which dissociates the Li₂CO₃. Lithium ions are passed throughthe composite layer 28 into catholyte 18 which is then processed intoLiOH solution. Alternatively, the obtained LiOH solution is delivered tothe stage of evaporation. Dehydration to produce LiOH monohydrate can beaccomplished by heating the high purity LiOH solution in a vacuum orunder the cover of an inert gas at a temperature of approximatelyambient temperatures or slightly above ambient temperatures. The driedcrystalline lithium hydroxide monohydrate (LiOH.H₂O) is then packaged ininert atmosphere.

In another embodiment a lithium hydroxide solution is the catholyte. Aslithium is processed through the membrane, both the concentration oflithium hydroxide and the solution pH increases. Periodically, portionsof the LiOH electrolyte solution can be bled off and dehydrated tolithium hydroxide monohydrate, replacing the solution removed withdeionized water to return it to the original concentration; a continuouscontrol, maintaining a specific concentration in the circulatingcatholyte, could also be used. In such cases, operating temperature canbe raised (though remaining below the boiling point of the LiOHelectrolyte) to increase conductivity of the membrane.

When using an aqueous electrolyte on both sides of the membrane of thecell, membranes not exhibiting extremely low moisture permeability canbe used. As such, a polyethylene oxide composite, garnet, or othersuitable membranes can be used for lithium hydroxide processing, or forany other aqueous catholyte-aqueous anolyte system.

The benefits of having a higher purity LiOH solution is advantageous inregards to reducing the number of purification steps resulting in energysaving in evaporation or a solution of conversion of LiOH in productionof LiOH.H₂O.

The lithium hydroxide monohydrate may be used as cathode material in alithium-ion battery. High purity lithium hydroxide is used in nickelcobalt aluminum (NCA) cathodes. The lithium hydroxide and lithiumhydroxide monohydrate may also be used as a heat transfer medium, astorage-battery electrolyte, a material in ceramics, or a material in acement formulation. The lithium hydroxide and lithium hydroxidemonohydrate may also be used in breathing gas purification systems forspacecraft, submarines and rebreathers to remove carbon dioxide fromexhaled gas to produce lithium carbonate and water according to one ofthe following reactions:

2LiOH.H₂O+CO₂→Li₂CO₃+2H₂O or

2LiOH+CO₂→Li₂CO₃+H₂O

The lithium hydroxide and lithium hydroxide monohydrate produced usingthe high purity lithium metal advantageously contains fewer impuritiesthan lithium hydroxide and lithium hydroxide monohydrate produced usingconventional lithium metal. For example, because the lithium hydroxideis formed using the high purity lithium metal, and deionized water, thelithium hydroxide does not contain mercury or nonconductive impuritiesassociated with lithium metal formed using conventional processes.Furthermore, the lithium hydroxide produced using the high puritylithium metal has a higher concentration of lithium than lithiumhydroxide and lithium hydroxide monohydrate currently on the market.Therefore, when the lithium hydroxide produced using the high puritylithium metal is used as a feedstock for a cathode material in alithium-ion battery, the active material is increased and the energydensity and performance of the lithium-ion battery are enhanced.

Conventional methods of producing lithium hydroxide and lithiumhydroxide monohydrate are complex and costly, requiring a large numberof purification steps, and the resulting purity levels are low.Therefore, by using the high purity lithium metal to produce lithiumhydroxide and lithium hydroxide monohydrate, the process costs will belowered and the supplies of lithium hydroxide and lithium hydroxidemonohydrate may be increased.

Suitable feed to the cell includes water-soluble lithium salts includingbut not limited to Li₂CO₃ (lithium carbonate) and LiCl. Lithiumcarbonate (Li₂CO₃) is the most readily available lithium salt, beingrelatively inexpensive and is a preferred lithium source. To improvesolubility, the lithium salt is dissolved in hydrated acid such assulfuric acid and used as electrolyte 18 in the electrolytic cell.

In an embodiment, recycling lithium feed from lithium batteries may, forexample, be accomplished by addition of sulfuric acid. The slurry ofrecycled lithium battery feed stock is placed into electrolyte 11 andprocessed with sulfuric acid to dissociate the solution. Current isapplied to the cell, and the lithium ions pass through the lithium ionconductive glass-ceramic (LiC-GC) layer into the catholyte for the highpurity lithium metal to be harvested at the cathode, exactly like theoriginal process.

Specifically, a sulfuric acid electrolyte may be used to disassociatelithium carbonate, placing the lithium ions into solution for processingand venting off the carbonate portion without it entering into solution.By disassociating the lithium carbonate and only placing the lithiumions into solution, the electrolyte solution remains stable and does notbuild up a concentration of the non-lithium ion portion of the feedstock. Lithium carbonate can be continuously fed into a tank outside ofthe electrolytic cell, venting off the CO₂ gas released by the sulfuricacid electrolyte. The acid electrolyte does not need to be disposed ofor replenished, lithium carbonate can be continuously added to a feedtank, venting off CO₂ and harvesting lithium metal from the cathode.This can be continuously operated or conducted as a batch process.

Cathode 16 is characterized by the intercalated composite lithium ionconductive glass-ceramic (LiC-GC)/lithium ion conductive barrier film(Li—BF) 28, e.g., the composite 28 is inserted or interposed between thecathode 16 and electrolyte 18. If both the catholyte and anolyte areaqueous, the membrane would not need to be LiC-GC; the membrane could bea polyethylene oxide composite, garnet, or other suitable membranes thatallow moisture permeation. The cathode 16 can be characterized as“transpositioning” meaning the cathode advances along an axis of thecell 10 to transpire produced lithium through the composite 28 and toisolate cathode-deposited lithium. The cathode comprises a suitablematerial that is non-reactive with lithium metal and the compositelayer. The lithium ion conductive glass-ceramic (LiC-GC)/lithium ionconductive barrier film (Li—BF) composite layer is a stationary barrierbetween the anode compartment and the lithium metal forming on thecathode. The cathode moves to accommodate the continuously thickeninglayer of lithium metal on the cathode.

The substantially impervious selective lithium-ion conducting (LiC-GC)layer 30 can be an active metal ion conducting glass or glass-ceramic(e.g., a lithium ion conductive glass-ceramic that has high active metalion conductivity and stability to aggressive electrolytes and compoundsincluding water that vigorously react with lithium metal). Suitablematerials are substantially impervious, ionically conductive, andchemically compatible with aqueous electrolytes, or other electrolytes(catholyte), and/or cathode materials that would otherwise adverselyreact with lithium metal. Such glass or glass-ceramic materials aresubstantially gap-free, non-swellable and are inherently ionicallyconductive (i.e., they do not depend on the presence of a liquidelectrolyte or other agent for their ionically conductive properties).Suitable glass or glass-ceramic materials also have high ionicconductivity, at least 10⁻⁷ S/cm, generally at least 10⁻⁶ S/cm, forexample at least 10⁻⁵ S/cm to 10⁻⁴ S/cm, and as high as 10⁻³ S/cm orhigher so that the overall ionic conductivity of the multi-layerprotective structure is at least 10⁻⁷ S/cm and as high as 10⁻³ S/cm orhigher. The thickness of the layer is preferably about 0.1 to 1000microns, or, where the ionic conductivity of the layer is about 10⁻⁷S/cm, about 0.25 to 1 micron, or, where the ionic conductivity of thelayer is between about 10⁻⁴ to about 10⁻³ S/cm, about 10 to 1000microns, preferably between 1 and 500 microns, and more preferablybetween 50 and 250 microns, for example, about 150 microns.

For processes using an aqueous electrolyte on both sides of the membraneof the cell, permeable membranes are suitable.

Examples of the lithium ion conductive glass-ceramic (LiC-GC) layer 30include glassy or amorphous metal ion conductors, such as aphosphorus-based glass, oxide-based glass, phosphorus-oxynitride-basedglass, sulfur-based glass, oxide/sulfide-based glass, selenide-basedglass, gallium-based glass, germanium-based glass or boracite glass(such as are described D. P. Button et al., Solid State Ionics, Vols.9-10, Part 1, 585-592 (December 1983); ceramic active metal ionconductors, such as lithium beta-alumina, sodium beta-alumina, Lisuperionic conductor (LISICON), Na superionic conductor (NASICON), andthe like; or glass-ceramic active metal ion conductors. Specificexamples include LiPON (nitrided lithium phosphate), Li₃PO₄, Li₂S, SiS₂,Li₂S, GeS₂, Ga₂S₃ and Li₂O. Examples of permeable membranes suitable forprocesses using aqueous electrolytes on both sides of the cell includepolyethylene oxide composites and garnet.

Suitable lithium ion conductive glass-ceramic (LiC-GC) materials includea lithium ion conductive glass-ceramic having the following compositionin mol percent: P₂O₅ 26-55%; SiO₂ 0-15%; GeO₂+TiO₂ 25-50% (in which GeO₂0-50%; TiO₂ 0-50%); ZrO₂ 0-10%; M₂O₃ 0-10%; Al₂O₃ 0-15%; Ga₂O₃ 0-15%;Li₂O₃ 0-25%; and containing a predominant crystalline phase comprisingLi_(1+x)(M, Al, Ga)x(Ge_(1−y)Ti_(y))_(2−x)(PO4)₃ where x≤0.8 and0≤y≤1.0, and where M is an element selected from the group consisting ofNd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb, and/orLi_(1+x+y)Q_(x)Ti_(2−x)Si₃P_(3-y)O₁₂, where 0<x≤0.4 and 0<y≤0.6, andwhere Q is Al or Ga. Other examples include Li₂O-11Al₂O₃, Na₂O-11Al₂O₃,(Na, Li),±_(x)Ti_(2−x)Al_(x)(PO₄)₃ (0.6<x≤0.9) and crystallographicallyrelated structures, Na₃Zr₂Si₂PO₁₂, Li₃Zr₂Si₂PO₄, Na₅ZrP₃O₁₂, Na₅TiP₃O₁₂,Na₃Fe₂P₃O₁₂, Na₄NbP₃O₁₂, Li₅ZrP₃O₁₂, Li₅TiP₃O₁₂, Li₅Fe₂P₃O₁₂,Li₄NbP₃O₁₂, Li₇La₃Zr₂O₂ (LLZO), and combinations thereof, optionallysintered or melted. Suitable ceramic ion active metal ion conductors aredescribed, for example, in U.S. Pat. No. 4,985,317 to Adachi et al.Suitable material also includes polymer composites of the above.Suitable material also includes membranes allowing moisture permeation,including polyethylene oxide composite and garnet.

Suitable lithium ion conductive glass-ceramic (LiC-GC) materials includea product from Ohara, Inc. (Kanagawa, JP), trademarked LIC-GC™, LISICON,Li₂O—Al₂O₃—SiO₂—P₂O₅—TiO₂ (LATP). Suitable material with similarly highlithium metal ion conductivity and environmental/chemical resistance aremanufactured by Ohara and others. See, for example, Inda, DN20100113243,now U.S. Pat. No. 8,476,174. U.S. Pat. No. 8,476,174 discloses aglass-ceramic comprising at least crystallines having a having aLiTi₂P₃O₁₂ structure, the crystallines satisfying 1<I_(A113)/I_(A104)≤2,wherein I_(A104) is the peak intensity assigned to the plane index 104(2θ=20 to 21°), and I_(A113) is the peak intensity assigned to the planeindex 113 (2θ=24 to 25°) as determined by X-ray diffractometry. Suitablematerial also includes membranes allowing moisture permeation, includingpolyethylene oxide composite and garnet.

The lithium ion conductive glass-ceramic (LiC-GC) layer 30 selectivelyallows only lithium ions to flow. Therefore, the resulting lithium metalproduced using electrolytic cell 10 has a high purity. The inventorbelieves that the resulting lithium metal has a purity of nearly 100%and at least greater than 99.9% on a metals basis.

The lithium ion conductive barrier film (Li—BF) 32 is a lithium metalion conductive film or coating with high lithium metal ion conductivity.The lithium ion conductive barrier film (Li—BF) 32 is a lithium metalion conductive film or coating with high lithium metal ion conductivity,typically 1.0 mS/cm to 100 mS/cm. A high lithium ion transference number(t₊) is preferred. Low t₊Li⁺ electrolytes will hinder performance byallowing ion concentration gradients within the cell, leading to highinternal resistances that may limit cell lifetime and limit reductionrates. Transference numbers between t₊=0.70 and t₊=1.0 are preferred.The lithium ion conductive barrier film is non-reactive to both lithiummetal and the lithium-ion conductive glass-ceramic (LiC-GC) material.

The lithium ion conductive barrier film (Li—BF) 32 may be an activemetal composite, where “active metals” include lithium, sodium,magnesium, calcium, and aluminum used as the active material ofbatteries. Suitable lithium ion conductive barrier film (Li—BF) materialincludes a composite reaction product of active metal with Cu₃N, activemetal nitrides, active metal phosphides, active metal halides, activemetal phosphorus sulfide glass, and active metal phosphorous oxynitrideglass (Cu₃N, L₃N, Li₃P, LiI, LiF, LiBr, LiCl and LiPON). The lithium ionconductive barrier film (Li—BF) material must also protect againstdendrites forming on the cathode from coming in contact with the lithiumion conductive glass-ceramic (LiC-GC) material. This may be accomplishedby creating physical distance between the cathode and the lithium ionconductive glass-ceramic (LiC-GC) and/or providing a physical barrierthat the dendrites do not penetrate easily. One preferred lithium ionconductive barrier film (Li—BF) is a physical organogel electrolyteproduced by in situ thermo-irreversible gelation and singleion-predominant conduction as described by Kim et al. in ScientificReports (article number: 1917 doi:10.1038/srep01917). This electrolytehas t₊=0.84 and conductivity of 8.63 mS/cm at room temperature. Thisorganogel electrolyte can be set up in a porous membrane to provideadditional structure and resistance to dendrite penetration. Typicalporous membrane thickness is 1 μm to 500 μm, for example 20 μm.Acceptable porous membranes include Hipore™ polyolefin flat-filmmembrane by Asahi Kasei E-materials Corporation.

A high purity lithium metal according to another embodiment may beproduced using a cell as shown in FIGS. 3A-3E. When producing lithiummetal, the membrane should be substantially impervious to mositure. Thecell of FIGS. 3A-3E shows a production system and process wherein highpurity lithium metal is extracted from a lithium ion containingelectrolyte 11. The electrolytic cell of FIG. 3D shows a sleeve 1 and acell body 3. In an embodiment, the cell body 3 can be made of a suitablyrigid material such as polypropylene. The high purity lithium andassociated products and processes described herein are not limited inthis regard. The cell includes a movable cathode 5 that transposes anaxis of the cell body 3 and can be positioned to variable heights abovea lithium ion conductive glass-ceramic (LiC-GC) membrane 2. With thecathode 5 positioned in catholyte 10 above the lithium ion conductiveglass-ceramic (LiC-GC) membrane 2, ion transfer can occur through alithium ion conductive glass-ceramic (LiC-GC) composite layer onto thecathode 5. The anode 20′ in this embodiment is provided in a lowerportion of cell body 3, and can be made of stainless steel for sulfuricacid resistance. Alternatively, the anode 20′ can be made from titaniumor niobium coated with platinum, gold, or ruthenium. The portion of cellbody 3 below the lithium ion conductive glass-ceramic (LiC-GC) membrane2 is loaded with lithium ion containing electrolyte via inlet 20,electrolysis proceeds and spent electrolyte is discharged via outlet 21.Lithium ions are conducted from the lithium ion containing electrolyte11, through the lithium ion conductive glass-ceramic (LiC-GC) membrane 2and lithium ion conducting catholyte 10 to the cathode 5.

The cathode 5 is spaced apart from the lithium ion conductiveglass-ceramic (LiC-GC) membrane 2 intercalated between the cathode 5 andelectrolyte 11. The composite layer comprises a lithium ion conductiveglass-ceramic layer (LiC-GC) 2 interposed between the lithium ioncontaining electrolyte 11 and the lithium ion conducting catholyte 10.The glass-ceramic layer 2 and the cathode spacing isolates lithiumforming at cathode 5 from electrolyte 11. Cathode support 6 is driven bya servo motor and advances the cathode 5 as required to maintain spacingbetween lithium metal formed on the cathode and the lithium ionconductive glass-ceramic (LiC-GC) membrane 2, and also to withdraw thecathode for lithium metal removal. The lithium metal produced at thesolid cathode 5 can be drawn off as a pure metallic phase.

Suitable cell components for the cell of FIG. 3 include many of the samecomponents as the embodiment of the lithium producing cell structuredescribed above in connection with FIG. 1, and also cell componentsdescribed in US20130004852. Suitable feed to the cell of FIG. 3 includesthe same materials disclosed for the embodiment of the lithium producingcell structure described above in connection with FIG. 1, specificallywater-soluble lithium salts including but not limited to Li₂CO₃ (lithiumcarbonate) and LiCl. To improve solubility, as with the embodiment ofthe lithium producing cell structure described above in connection withFIG. 1, the lithium salt is dissolved in hydrated acid such as sulfuricacid and used as electrolyte 11 in the cell of FIG. 3. The acidelectrolyte does not need to be disposed of or replenished, lithiumcarbonate can be continuously added to a feed tank, venting off CO₂ andharvesting lithium metal from a cathode. This can be continuouslyoperated or conducted as a batch process.

Cathode 5 is characterized by the intercalated lithium ion conductiveglass-ceramic (LiC-GC) membrane 2 inserted or interposed between thecathode 5 and electrolyte 11. The cathode 5 can be characterized as“transpositioning” meaning the cathode advances along an axis of thecell body 3 to transpire produced lithium through the catholyte 10 andto isolate cathode-deposited lithium. The cathode comprises a suitablematerial that is nonreactive with lithium metal and the composite layer.The lithium ion conductive glass-ceramic (LiC-GC) membrane 2 is astationary barrier between the electrolyte 11 in the anode compartmentand the catholyte 10 on the cathode side of the cell, allowing onlylithium ion conduction through the membrane. The cathode 5 moves toposition the cathode at the proper distance from the lithium ionconductive glass-ceramic (LiC-GC) membrane 2 during deposition, andretracts to allow deposited lithium metal to be harvested.

The selective lithium ion conductive glass-ceramic (LiC-GC) membrane 2is a lithium ion conductive glass-ceramic layer. Suitable materials forthe glass-ceramic layer include the same materials for the lithium ionconductive glass-ceramic (LiC-GC) layer 30 of the embodiment of thelithium producing cell structure described above in connection with FIG.1.

For example, suitable materials for the glass-ceramic layer areelectrically insulating, substantially impervious, ionically conductive,and chemically compatible with aqueous electrolytes, or otherelectrolytes (catholytes), and/or cathode materials that would otherwiseadversely react with lithium metal. Such materials also have high ionicconductivity, at least 10⁻⁷ S/cm, generally at least 10⁻⁶ S/cm, forexample at least 10⁻⁵ S/cm to 10⁻⁴ S/cm, and as high as 10⁻³ S/cm orhigher, so that the overall ionic conductivity of the multi-layerprotective structure is at least 10⁻⁷ S/cm and as high as 10⁻³ S/cm orhigher. The thickness of the layer is preferably about 0.1 to 1000microns, or, where the ionic conductivity of the layer is about 10⁻⁷S/cm, about 0.25 to 1 micron, or, where the ionic conductivity of thelayer is between about 10⁻⁴ S/cm to about 10⁻³ S/cm, about 10 to 1000microns, preferably between 1 and 500 microns, and more preferablybetween 50 and 250 microns, for example, about 150 microns.

A lithium ion conducting catholyte 10 must be present between thecathode 5 and lithium ion conductive glass-ceramic (LiC-GC) membrane 2to allow conduction of lithium ions to the cathode 5 from theelectrolyte 11. This can be a simple lithium battery electrolyte such asa mixture of ethylene carbonate (“EC”), dimethyl carbonate (“DMC”) andan electrolyte salt such as lithium hexafluorophosphate (LiPF₆), amixture of dimethyl carbonate and lithium hexafluorophosphate(DMC-LiPF₆). an Ionic Liquid TFSI (trifluoromethanesulfonyl-imide)-basedelectrolyte such as N-butyl-N-methylpyrrolidiniumbis(trifluoromethanesulfonyl)imide (Pyr₁₄TFSI), 1,3-dioxolane ethyleneglycol methylene ether, formaldehyde ethylene acetal, a solution of LLZO(Li₇La₃Zr₂O₂) and Ionic Liquid trifluoromethanesulfonyl-imide, Libis(trifluoromethanesulfonyl)imide (LiTFSI) in1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide(EMI-TFSI), ether based electrolytes, anhydrous dioxolane with a smallamount of BHT (butylated hydroxy toluene). In an embodiment, 1 M lithiumbis(trifluoromethanesulphonyl)imide (LiTFSI) in 1,3-dioxolane and1,2-dimethoxyethane (volume ratio 1:1) can be used with 1% lithiumnitrate (LiNO₃) and 100 mM Li₂S₈ additives as the electrolyte. Thepresence of LiNO₃ and Li₂S₈ helps in the formation of a stable solidelectrolyte interphase (SEI) on the lithium metal collecting cathode.Tetraglyme and Dioxolane combinations are also candidates. A morecomplex lithium ion conducting barrier film (Li—BF) is also a candidate.The use of a simple liquid electrolyte compatible with lithium metalgreatly simplifies cell assembly and harvesting of deposited lithium ascompared with the process disclosed in U.S. patent application Ser. No.14/328,613. With the cell properly constructed (cathode 5 facing up) theliquid electrolyte can be poured into the space above the lithium ionconductive glass-ceramic (LiC-GC) membrane 2, on the cathode side of thecell, and the cathode simply lowered into the electrolyte to performdeposition, or withdrawn from the electrolyte to harvest depositedmetal.

The electrolyte can be modified in the catholyte to produce a desiredsolid electrolyte interphase (SEI) layer, or none at all.

A lithium ion conductive film (Li—BF) 32 can be present. However, thecathode spacing aspect of the present disclosure can eliminate thiselement. If present, the conductive barrier film is a lithium metal ionconductive film with high lithium metal ion conductivity. Suitablelithium ion conductive barrier films (Li—BF) include the same materialsdisclosed for lithium ion conductive barrier film (Li—BF) 32 of theembodiment of the lithium producing cell structure described above inconnection with FIG. 1.

In the process using the cell of FIG. 3, anode and cathode compartmentsare electrically isolated to prevent electrolysis of water at highervoltages. The only ion transfer is through the lithium ion conductiveglass-ceramic (LiC-GC) membrane, which selectively allows only lithiumions to flow. Therefore, the resulting lithium metal has a high purity.The inventor believes that the lithium metal has a purity of nearly 100weight percent on a metals basis and at least greater than 99.99 weightpercent on a metals basis.

The cathode support can be a linear slide in the z-axis (up and down).This can be a pneumatic cylinder with end stops to control travel(lowest cost), or a servo drive to precisely position (higher cost butmore precise). With the cylinder retracted there is no electrolysis.When the cylinder extends it lowers the cathode into the electrolyte(while maintaining an electrolyte-filled space between the cathode andthe lithium ion conductive glass-ceramic (LiC-GC) plate). Voltage issupplied to reduce lithium ions to lithium metal on the cathode. At anypoint the cathode can be withdrawn by retracting the cylinder, at whichtime electrolysis is stopped and the lithium metal is harvested from thecathode.

In another embodiment, lithium metal produced from a lithium ioncontaining electrolyte is directly coated onto a strip of material usinga strip coating system as shown in FIG. 6. Specifically, a high puritylithium metal can be coated onto a strip foil substrate such asaluminum, copper or nickel using this strip coating system. The stripfoil substrate is connected to a plating power supply and acts as acathode when submersed in a catholyte in a strip coating tank. A lithiumion containing electrolyte is separated from the catholyte by a lithiumion conductive glass-ceramic (LiC-GC) membrane. The lithium ioncontaining electrolyte flows through the bottom of the strip coatingtank so that lithium ions are selectively conducted from the electrolytethrough the catholyte and the lithium ion conductive glass-ceramic(LiC-GC) membrane and lithium metal is deposited on the strip foilsubstrate.

The catholyte of FIG. 6 may have the same composition as catholyte 10described above in connection with FIG. 3. For example, the catholytemay be a simple lithium battery electrolyte such as a mixture ofethylene carbonate (EC), dimethyl carbonate (DMC) and an electrolytesalt such as lithium hexafluorophosphate (LiPF₆), a mixture of dimethylcarbonate and lithium hexafluorophosphate (DMC-LiPF₆), or a more complexlithium ion conducting barrier film.

The selective lithium ion lithium ion conductive glass-ceramic (LiC-GC)membrane is a lithium ion conductive glass-ceramic layer. Suitablematerials for the glass-ceramic layer include the same materials for thelithium ion conductive glass-ceramic (LiC-GC) layer 30 of theembodiments of the lithium producing cell structure described above inconnection with FIG. 1 or 3.

The lithium ion containing electrolyte is an electrolyte containinglithium ions and may have the same composition as electrolyte 18 of theembodiment described above in connection with FIG. 1 or the electrolyte11 of the embodiment described above in connection with FIG. 3. Forexample, the lithium ion containing electrolyte may comprise a lithiumsalt such as lithium carbonate that is dissolved in hydrated acid suchas sulfuric acid. A preferred electrolyte is a sulfuric acid electrolytethat contains lithium ions.

In another embodiment, lithium metal produced from a lithium ioncontaining electrolyte is directly coated onto a strip of material, andis then converted to a lithium compound using a continuous strip coatingsystem as shown in FIG. 7. High purity lithium metal is coated onto acontinuous strip material such as aluminum, copper, graphite coatedcopper, or nickel using this strip coating system. The continuous stripmaterial is connected to a plating power supply and acts as a cathodewhen submersed in a catholyte in a strip coating tank. A lithium ioncontaining electrolyte is separated from the catholyte by a lithium ionconductive glass-ceramic (LiC-GC) membrane. The lithium ion containingelectrolyte flows through the bottom of the strip coating tank so thatlithium ions are selectively conducted from the electrolyte through thecatholyte and the lithium ion conductive glass-ceramic (LiC-GC) membraneand lithium metal is deposited on the continuous strip material.

As shown in FIG. 7, the lithium-coated strip material may then becontinuously fed into a system for producing a lithium compound such aslithium hydroxide. Specifically, the high purity lithium metal may beprocessed with deionized water to form lithium hydroxide and hydrogenaccording to the following reaction:

2Li+2H₂O→2LiOH+H₂

The hydrogen produced in this lithium hydroxide formation process may bevented off, burned off or stored. For example, the hydrogen may beburned off in air to form water, or simply vented to the atmospherewhere it will combine with oxygen to form water vapor. Alternatively,the hydrogen may be captured in capsules or cartridges. The capsules orcartridges containing hydrogen may be used as rechargeable cartridges ina fuel cell battery for consumer electronics.

A high purity lithium metal according to another embodiment may beproduced using a cell as shown in FIG. 9. Suitable cell components forthe cell of FIG. 9 include most of the same components disclosed for theprevious embodiments of the lithium producing cell structure,specifically most of those cell components described in US20130004852.This embodiment eliminates the separate anode structure, and simplifieselectrical connection to anode and sealing of an electrical connection.As seen in FIG. 9, the separate anode structure has been replaced by aconductive cell body 3′, which now acts as the anode. The cell body 3′in this embodiment can be made of 904L stainless steel for sulfuric acidresistance. In a further embodiment, the cell body 3′ can be made of904L stainless steel with the inside flow surfaces plated with gold,platinum, ruthenium oxide, or other conductive material that has goodconductive properties and is resistant to sulfuric acid. The lithium ionconductive glass-ceramic (LiC-GC) membrane 2 is bonded to non-conductivecell sleeve 1, providing a barrier between catholyte 5 and anolyte. Thecatholyte 5 in this embodiment is non-flowing for direct deposition ontoa substrate. Square O-ring 4 seals the cell body 3′ to cell sleeve 1.

Suitable feed to the cell of FIG. 9 includes the same materialsdisclosed for the previous embodiments of the lithium producing cellstructure, specifically water-soluble lithium salts including but notlimited to Li₂CO₃ (lithium carbonate) and LiCl. To improve solubility,as with the previous embodiments, the lithium salt is dissolved inhydrated acid such as sulfuric acid and used as electrolyte in the cellof FIG. 9.

The selective lithium ion conductive glass-ceramic (LiC-GC) membrane 2is a lithium ion conductive glass-ceramic layer. Suitable materials forthe glass-ceramic layer include the same materials for the lithium-ionconducting layer of the previous embodiments of the lithium producingcell structure. The electrolyte can be modified in the catholyte toproduce a desired solid electrolyte interphase (SEI) layer, or none atall.

In the process using the cell of FIG. 9, anode and cathode compartmentsare electrically isolated to prevent electrolysis of water at highervoltages. The only ion transfer is through the lithium ion conductiveglass-ceramic (LiC-GC) membrane, which selectively allows only lithiumions to flow. Therefore, the resulting lithium metal has a high purity.

A high purity lithium metal according to another embodiment may beproduced using a cell as shown in FIGS. 10A-10B. Suitable materials forthe glass ceramic layer, cell components, feed, and electrolyte for thecell of FIGS. 10A-10B include the same materials for the glass ceramiclayer, cell components, feed, and electrolyte disclosed for the cell ofFIG. 9. This embodiment, like the cell of FIG. 9, eliminates theseparate anode structure, and simplifies electrical connection to anodeand sealing of an electrical connection. Unlike the cell of FIG. 9,FIGS. 10A-10B depict a cell with a closed top with catholyte flowingthrough the top half of the cell. The flowing catholyte is thenprocessed to form LiOH.

The lithium metal produced according to certain embodiments has a highpurity due to the selective conduction of lithium ions out of thelithium containing electrolyte. The inventor believes that the lithiummetal produced according to certain embodiments has a purity of nearly100 weight percent, and at least greater than 99.99 weight percent on ametals basis, or at least greater than 99.998 weight percent, due to theuse of the selective lithium ion conducting layer. As further explainedbelow, in an embodiment the inductively coupled plasma mass spectrometry(ICP-MS) analysis showed no presence of common impurities or base metalssuch as sodium, calcium, potassium, boron, magnesium, copper, iron,chlorine, aluminum, nitrogen, or silicon. The resulting high puritylithium metal may be used to make a lithium metal product and otherproducts containing lithium metal.

In another embodiment, lithium metal produced from a lithium ioncontaining electrolyte is directly coated onto a strip of material andis then converted to a lithium compound using a continuous strip coatingsystem as shown in FIG. 8. The roll of film to be coated is loaded ontopayoff reel 46 with tension clutch 9. The film is thread under stripguide 40 and onto takeup reel 96. Polypropylene film 95 can also bethreaded onto takeup reel 96 if desired to separate each layer of film.Tension clutch 92 controls the tension. Catholyte 33 is loaded intocavity above lithium ion conductive glass-ceramic (LiC-GC) plates 39.Platform 47 is raised to submerse submerse guide/film 40/46 in catholyte33. Variable speed drive 2 controls film speed through the bath. DCvoltage applied to the conductive housing of cell base 32 and the rotarycontactors 71 at payoff and takeup reels. The energized strip is thecathode and cell base 32 is the anode. The film is processed through abath at a controlled speed and voltage profile in order to coat filmwith high purity lithium metal at a desired thickness and morphology.

In an embodiment, the high purity lithium metal has a lithium purity ofat least 99.99 weight percent on a metals basis when analyzed using aninductively coupled plasma mass spectrometry (ICP-MS) method. Theremaining weight is representative of the resulting solid electrolyteinterphase (SEI) layer produced from decomposition of catholyte. In anembodiment, 100% weight lithium can be produced upon entering thecatholyte. This was verified by an inductively coupled plasma massspectrometry (ICP-MS) method, where the high purity lithium metal isionized with inductively coupled plasma and then subjected to massspectrometry to separate and quantify the ions in the high puritylithium metal. In the inductively coupled plasma mass spectrometry(ICP-MS) method, the lithium metal may be placed in a <5% nitric acidsolution that is free of particulates >0.45 μm in size and contains <2%organic materials. The total dissolved solids (“TDS”) in the solutionmust be below 0.1% when diluted for inductively coupled plasma massspectrometry (ICP-MS) determination. The inductively coupled plasma massspectrometry (ICP-MS) analysis may be performed using a suitableinductively coupled plasma mass spectrometry (ICP-MS) instrument.

An embodiment of the high purity lithium metal of the present disclosureanalyzed by the inductively coupled plasma mass spectrometry (ICP-MS)method contains, in parts per million by weight, less than 0.6 silver(Ag), less than 2 aluminum (Al), less than 0.2 arsenic (As), less than0.1 gold (Au), less than 0.4 boron (B), less than 0.4 barium (Ba), lessthan 0.5 beryllium (Be), less than 0.1 bismuth (Bi), less than 4 calcium(Ca), less than 0.5 cadmium (Cd), less than 0.4 cerium (Ce), less than0.4 cobalt (Co), less than 0.4 chromium (Cr), less than 0.4 cesium (Cs),less than 0.4 copper (Cu), less than 0.4 dysprosium (Dy), less than 0.4erbium (Er), less than 0.5 europium (Eu), less than 0.7 iron (Fe), lessthan 0.4 gallium (Ga), less than 0.4 gadolinium (Gd), less than 0.3germanium (Ge), less than 0.2 hafnium (Hf), less than 0.3 mercury (Hg),less than 0.3 holmium (Ho), less than 0.5 indium (In), less than 0.2iridium (Ir), less than 0.5 potassium (K), less than 0.4 lanthanum (La),less than 0.1 lutetium (Lu), less than 5 magnesium (Mg), less than 0.3manganese (Mn), less than 0.4 molybdenum (Mo), less than 0.3 niobium(Nb), less than 0.4 neodymium (Nd), less than 0.9 nickel (Ni), less than0.4 osmium (Os), less than 10 phosphorus (P), less than 0.1 lead (Pb),less than 0.5 palladium (Pd), less than 0.4 praseodymium (Pr), less than0.2 platinum (Pt), less than 0.4 rubidium (Rb), less than 0.1 rhenium(Re), less than 0.3 rhodium (Rh), less than 0.4 ruthenium (Ru), lessthan 13 sodium (Na), less than 19 sulfur (S), less than 0.3 antimony(Sb), less than 0.5 scandium (Sc), less than 1 selenium (Se), less than69 silicon (Si), less than 0.5 samarium (Sm), less than 0.7 tin (Sn),less than 0.5 strontium (Sr), less than 0.1 tantalum (Ta), less than 0.3terbium (Tb), less than 0.4 tellurium (Te), less than 0.1 thorium (Th),less than 0.4 titanium (Ti), less than 0.1 thallium (Tl), less than 0.2thulium (Tm), less than 0.1 uranium (U), less than 0.5 vanadium (V),less than 0.2 tungsten (W), less than 0.4 yttrium (Y), less than 0.2ytterbium (Yb), less than 1 zinc (Zn), and less than 0.3 zirconium (Zr).Thus, the total impurities in the lithium metal are less than 0.002weight percent.

In an embodiment, the high purity lithium metal has a lithium purity ofat least 99.998 weight percent on a metals basis. In an embodiment, thehigh purity lithium metal has no impurities above the minimum detectablelimit of the inductively coupled plasma mass spectrometry method(ICP-MS) method. In an embodiment, the high purity lithium metal has noimpurities.

Depending on the parameters, such as applied current and voltage, thelithium obtained according to an embodiment of the present disclosurecan assume a nanorod morphology. As opposed to the lithium foil obtainedby conventional processes, the self aligned nanorods provide a highersurface area for lower impedance and increased rate capability. Thenanorod morphology also has the benefits of a highly desirable diffusioncoefficient and flexible deposition. Moreover, the lithium is free of avariety of non-conductive contaminants and impurities which can causeundesirable side reactions. The micrographs of FIGS. 11A-11B illustratethe difference between a lithium foil obtained by a prior art processand a lithium nanorod obtained via the current disclosure. On the rightside of FIG. 11A, the three different micrographs show a lithium filmaccording to the present disclosure (99.998% metals basis; 100 μmthickness) on copper having an unexpected self aligned nano-rodmorphology (300 nm diameter×100 μm length) of the electro-depositedlithium metal. Notably, this nano-rod configuration has a smoothersurface that is dendrite free. In contrast, the three differentmicrographs of the prior art lithium foil (99.9% metals basis; 750 μmthickness) show a surface with dendrite arms, as well as surface defectsand cracks which serve as nucleation sites for further dendrite growth.

FIG. 12 shows two optical micrographs of lithium samples according tothe present disclosure on copper. The weight for the lithium metal filmis 50 mg. The dimensions for the copper foil substrate are 3 cm×3 cm(area)×125 μm thickness. Regarding the sample on the right side of FIG.12, a bluish color was observed for the film, which is a positiveindication of film purity and smoothness. The blue appearance might bedue to a structural coloration effect, whereby the fine microscopicsurface produces a structural color by interference among light wavesscattered by two or surfaces of the thin film.

In an embodiment, the present disclosure provides a process forseparating Lithium-6 and Lithium-7 isotopes from a lithium metal, theprocess comprising: providing an electrolytic cell comprising an organicaqueous solution, a nonaqueous electrolyte and a selective lithium ionconducting membrane, and causing the Lithium-6 and Lithium-7 isotopes inthe lithium metal to pass through the membrane at different velocities,and capturing at least one of the Lithium-6 and Lithium-7 isotopes. Thisprocess can, for example, be run at least two times using a specificelectrolyte. Suitable electrolytes include crown ethers such as18-Crown-6 [C₂H₄O]₆ and 2,2,2-cryptate; both form very stable complexesin both gas and solution phase, and have a high affinity for cations.Other suitable solvents include dimethylformamide (DMF) (CH₃)₂NC(O)H,and dimethyl sulfoxide (DMSO) (CH₃)₂SO, both polar aprotic solvents, anddimethylacetamide (DMA) CH₃C(O)N(CH₃)₂. Polyethelene glycol (PEG) mixedwith ammonium sulfate (NH₄)₂SO₄ and solvents producing differentsolvation states for lithium ions in two aqueous phases produce a usableseparation factor. Macrolyclic polyethers offset solvation of the cationby water molecules in the PEG rich phase.

For separation of Li-6 and Li-7 isotopes, an aqueous electrolyte couldbe used on both sides of the membrane until the final metal depositionstage. Multiple aqueous-aqueous stages could be used to enrich with thefinal deposition stage using a non-aqueous electrolyte. For theaqueous-aqueous stages, the LiC-GC membrane could be used, or anothermembrane such as a polyethylene composite or garnet, which allow forproton transfer, could be used. The final deposition stage which uses anon-aqueous electrolyte would require a membrane with extremely lowmoisture permeability such as the LiC-GC membrane.

In an embodiment, the present disclosure provides a process to obtain anenriched Lithium-6 isotope and/or an enriched Lithium-7 isotope fromLithium metal. The enrichment process was performed using the cell ofFIG. 3. Samples of Li₂CO₃ (feedstock) and the resulting two samples ofLithium metal products were analyzed for isotopic ratio. In one example,a decrease in lithium-7 fraction by approximately 1.04 and an increasein lithium-6 fraction by approximately 1.17% was observed.

The high purity lithium-7 and lithium-6 may be used for applications innuclear power. For example, lithium-7 hydroxide is used as an additivein pressurized water reactor cooling systems as a pH stabilizer, andlithium-6 is a source of tritium for nuclear fusion.

The high purity lithium may advantageously be used in the followingproducts: a lithium metal electrode, preferably a lithium metal anode;and a battery including the lithium metal electrode, preferably alithium primary battery or a rechargeable battery having a lithium metalanode. By including the high purity lithium in a lithium metal electrodeof a battery, the electrode should not induce the formation of dendriteswhen undergoing charge and discharge cycles (due to the presence offewer impurities), and, thus, a battery containing the high puritylithium metal electrode advantageously achieves a high energy densitywhile simultaneously achieving good safety due to the reduction ofshort-circuiting caused by dendrite formation.

In another embodiment, the present disclosure provides an improvedlithium battery containing the high purity lithium. The improved lithiumbattery may include a lithium metal electrode containing the high puritylithium. The lithium metal electrode containing the high purity lithiummay preferably be used as an anode in the improved lithium battery. Theimproved lithium battery advantageously does not contribute to dendritegrowth during cycling than batteries having a lithium metal electrodewith a lower lithium purity (i.e., 99.9% or less). Therefore, theimproved lithium metal battery may be a primary battery or arechargeable battery that undergoes repeated charge and discharge cycleswithout significant dendrite formation. The improved lithium metalbattery may use an electrode produced with a protective layer via atomiclayer deposition (ALD), and a specific solid electrolyte interphase(SEI) controlled by the catholyte. The improved lithium metal batteryadvantageously achieves a high energy density, cycle life, ratecapability and low impedance and can withstand pulse withoutcompromising battery safety due to short-circuiting caused by dendriteformation.

Alternatively, the improved lithium battery may include an electrodecontaining a lithium compound formed using the high purity lithium. Thelithium compound may be any known lithium compound that is used for anelectrode in a lithium battery, including but not limited to: a lithiumoxide containing cobalt, nickel, aluminum, manganese or mixturesthereof, such as lithium cobalt oxide (LiCoO₂) or lithium nickelate(LiNiO₂); a lithium phosphate such as lithium cobalt phosphate(LiCoPO₄), lithium iron phosphate (LiFePO₄) or lithium manganesephosphate (LiMnPO₄); a lithium chalcogenide such as LiTiS₂ or LiVSe₂; alithium layered oxide; and a lithium alloy. When the high purity lithiummetal is used to form the lithium compound in the electrode, the overalllithium compound has a high purity and does not contain the impuritiestypically associated with lithium metal, the concentration of the activematerial is increased, and, thus, battery characteristics such as cyclelife, charge-discharge rate capability, and impedance can be improved.

The improved lithium battery may advantageously be used in productsincluding but not limited to portable consumer electronic devices,military batteries, micro batteries, lithium-ion batteries, space(wearable and craft) and satellite batteries, drone batteries, flexiblebatteries, sensor batteries that can withstand a pulse, medical devices,toys, clocks, cameras and oceanographic equipment, or devices using“Battery on Board”, a battery meant to exceed the life of the product.For example, the improved lithium battery may be used in a camera suchas a digital camera. Digital cameras and drones are notorious fordraining battery life due to high energy consumption by the LCD screen(which contains lithium) and the motors that move the mechanicalcomponents of the camera. Therefore, it is desirable to have a digitalcamera that has a higher energy density and longer battery life so thatthe camera does not shut down at undesirable times when trying to take apicture. Conventional lithium metal primary batteries have a high energydensity and can therefore be made more compact and have a longer batterylife as compared with lithium ion batteries. However, such primarybatteries suffer dendrite formation due to the impurities in the lithiummetal anode, and do not handle electrochemical pulses well, and uselithium of significantly less purity. By using a lithium metal batterycontaining an anode having the high purity lithium as described above,the active material (lithium metal) is increased, resulting insubstantially longer life, capacity, lower impedance and dendriteformation can be reduced or eliminated, thereby giving the digitalcamera a longer battery life and higher safety as compared withconventional lithium metal batteries. Alternatively, by using a lithiumbattery including an electrode containing a lithium compound formedusing the high purity lithium, the impurities in the electrode materialcan be reduced, thereby improving the cycle life so that the digitalcamera has a longer battery life.

The improved lithium battery may also be used in a camcorder. A longerbattery life is desirable for camcorders so that they can record eventsthat have a longer duration or a series of shorter events withoutneeding to frequently replace or recharge the battery. A battery with ahigh energy density is also desirable so that the camcorder can be mademore compact and, thus, easier to carry and hold when recording. Byusing a lithium metal battery containing an anode having the high puritylithium as described above, dendrite formation can be reduced whilesimultaneously achieving a high energy density, thereby giving thecamcorder a longer battery life and higher safety without unnecessarybulkiness. Alternatively, by using a lithium battery including anelectrode containing a lithium compound formed using the high puritylithium, the impurities in the electrode material can be reduced,thereby giving the camcorder a longer battery life.

The improved lithium battery may also be used in a computer such as alaptop computer or a tablet computer. The most common type of batteryused in portable computers such as a laptop or tablet is a lithium ionrechargeable battery. By using a lithium battery, for example a lithiumion battery, including an electrode containing a lithium compound formedusing the high purity lithium as described above, the computer can havea longer cycle life and, thus, the computer will not need to berecharged as often as conventional lithium ion batteries. As a result,the computer can be used for longer periods of time without needing tobe plugged in or recharged. By using a lithium metal battery having alithium metal anode containing the high purity lithium as describedabove, the battery life and energy density of the computer battery canbe further improved as compared with conventional lithium ion batteries,without compromising the safety of the computer. Therefore, the computercan be made more compact and have a longer battery life. Furthermore,the battery will be less prone to “swelling” and, thus, the computerwill be less prone to heating up during use.

The improved lithium battery may also be used in a cellular phone suchas a smart phone. Cellular phones need compact batteries so that thecellular phone may be made smaller and, thus, more easily portable.However, cellular phones such as smart phones also use a lot of power,since many such phones include LCD screens (which contain lithium),cameras and video recorders. Therefore, it is desirable to provide acellular phone that can be made compact but also has a high energydensity. By using a lithium metal battery having a lithium metal anodecontaining the high purity lithium as described above, the high energydensity of lithium metal can be utilized to provide more power with asmaller battery, as well as a longer battery life as compared withconventional lithium ion batteries used in cellular phones. Even if thehigh purity lithium metal is used to form a lithium compound in alithium ion battery, a cellular phone containing such a lithium ionbattery will have a longer cycle life than conventional lithium ionbatteries due to the improved purity of the lithium compound in theelectrode and the lack of impurities associated with lithium produced byconventional processes.

The improved lithium battery may also be used in a personal digitalassistant. Like cellular phones, personal digital assistants (“PDAs”)are portable but require high power to store a significant amount ofdata and, thus, it is desirable to make personal digital assistants ascompact as possible while also achieving a high energy density. By usinga lithium metal battery having a lithium metal anode containing the highpurity lithium as described above, the personal digital assistant canmake use of the high energy density of lithium metal to provide a morecompact design while also having a high amount of power. In addition,because the amount of impurities in the lithium metal anode is reduced,dendrite formation is inhibited and, thus, the personal digitalassistant has both high safety and high energy density. Alternatively,if the personal digital assistant includes a lithium battery, forexample a lithium ion battery, using a lithium compound electrodematerial containing the high purity lithium as described above, thepersonal digital assistant can have a longer cycle life and, thus, willnot need to be recharged as often as a personal digital assistant usinga conventional lithium ion battery.

The improved lithium battery may also be used in small devices such as aclock, a watch, a remote car lock, a remote control for an audio oraudiovisual device such as a television, a remote control for smart homedevices, sensors, drones, a DVD player, a compact disc player, or amedia streamer. Due to the small size of these devices, a very compactbattery that provides a high energy density is required. Therefore,these devices may desirably include a lithium metal battery using ananode containing the high purity lithium as described above. By usingsuch a lithium metal battery, the small remote control devices can makeuse of the high energy density of lithium metal to provide a morecompact design while avoiding the problems associated with dendriteformation in most lithium metal batteries. Alternatively, if the devicesinclude a lithium ion battery containing the high purity lithium metal(e.g., the high purity lithium metal is used to form a lithium compoundused in the electrode), the remote control devices will have a longercycle life than devices using a conventional lithium ion battery.

The improved lithium battery may also be used in an electric vehicle.Lithium ion batteries are desirable for use in electric vehicles due totheir small size and low weight, as well as their charge efficiency.However, an electric vehicle containing a lithium ion battery using thehigh purity lithium metal (e.g., the high purity lithium metal is usedto form a lithium compound used in the electrode) will have a higherenergy density than conventional lithium ion batteries, and, thus, theelectric vehicle will be able to provide more power without increasingthe battery size. The electric vehicle can be further improved by usinga lithium metal battery containing the high purity lithium metal as ananode, cathode or electrolyte material. Because the lithium metal anodehas fewer impurities, dendrite formation will be inhibited and, thus,the electric vehicle will be able to utilize the high energy density oflithium metal without suffering the safety issues associated withdendrite formation. As a result, the electric vehicle can provide morepower and a longer battery life without increasing the battery size. Inan embodiment, the electric vehicle may also be less prone to fires dueto the improved lithium metal purity.

The improved lithium battery may also be used in implantable medicaldevices such as a cardiac pacemaker, a drug delivery system such as aninsulin pump, a neurostimulator, implantable sleep apnea device, a deepbrain neurostimulator, gastric stimulators, a cardiac defibrillator, aventricular assist device, a hearing assist device such as a cochlearimplant, a contact lens that measures glucose of tears and wirelesslytransmits data to a medical doctor, a cardiac resynchronization device,a bone growth generator, and an artificial heart. Because implantablemedical devices are typically essential to a patient's health, it isundesirable to leave the responsibility for charging the battery to thepatient. Implantable medical devices also need a long battery life sothat they do not have to be replaced often with invasive medicalprocedures. Therefore, these medical devices commonly use lithiumprimary batteries having a lithium metal anode. By using a lithium metalbattery including an anode formed of the high purity lithium metal asdescribed above, dendrite formation can be reduced and, thus, the highenergy density and long battery life associated with lithium metalanodes can be utilized to provide an implantable device having a longbattery life without the short-circuiting and safety problems associatedwith conventional lithium primary batteries. The improved thin filmlithium solid state battery may also be used in external medicaldevices.

The improved lithium battery may also be used in oceanographicequipment. Oceanographers often work in remote locations that aredifficult and costly to travel to and, thus, the oceanographers needbattery packs having a longer life so that the oceanographic equipmentdoes not need to be serviced as often. By using a lithium metal batteryhaving an anode containing the high purity lithium as described above,the oceanographic equipment can have a longer battery life without theassociated safety/dendrite formation problems associated withconventional lithium primary batteries. The improved lithium batterywith a specific solid electrolyte interphase (SEI) layer will improvethe safety and performance of batteries used in oceanographicapplications, such as water drones and other devices.

The improved lithium battery may be a lithium primary battery, arechargeable lithium metal battery, a rechargeable lithium-ion battery,a thin film lithium-ion battery, a micro battery, a flexible thin filmbattery, a lithium-ion polymer battery, a lithium iron phosphatebattery, a lithium sulfur battery, a lithium-air or metal-air battery,solid state rechargeable battery, or a nanowire battery. When theimproved lithium battery includes a lithium metal electrode, anode orelectrolyte containing the high purity lithium, the batteryadvantageously achieves a high energy density without compromisingbattery safety due to short-circuiting caused by dendrite formation.When the improved lithium battery includes an electrode containing alithium compound formed using the high purity lithium, batterycharacteristics such as cycle life and charge-discharge rate capabilitycan be improved due to the enhanced overall purity of the lithiumcompound.

The high purity lithium may advantageously be used as a flux for weldingor soldering applications to absorb impurities and thereby promote thefusing of metals. Because the lithium metal has a higher purity thanlithium metal currently on the market, the flux is able to absorb moreimpurities and thus better promote the fusing of metals by preventingoxidation of the metals to be fused.

The high purity lithium may also advantageously be used in alloys orcompounds containing lithium. For example, lithium salts containing thehigh purity lithium, such as lithium carbonate, lithium citrate andlithium orotate, may be used in the pharmaceutical industry as moodstabilizers to treat psychiatric disorders such as depression andbipolar disorder. Purity is especially important in medicinal productsdue to their use by humans or other animals. By providing the medicinalcompound containing the high purity lithium metal as described above,the overall purity of the compound can be improved as compared withlithium compounds prepared using lithium metal produced by conventionalprocesses. As another lithium alloy example, Alcoa uses a lithiumaluminum alloy in the body of airplanes to make them lighter. Usinghigher purity lithium decreases impurities in the alloy, improving theperformance and reducing interstitial defects. Improved alloy could beused in the frame of an electric vehicle (EV) to lighten the weightresulting in longer lasting driving range.

The high purity lithium may also be used in a lithium soap such aslithium stearate; a grease containing a lithium soap; lithium oxide;ovenware containing a lithium oxide; lithium fluoride; an opticalmaterial containing lithium fluoride; an optical material containing alithium compound; an organolithium compound; a polymer containing anorganolithium compound; lithium hydride; and an alloy containing lithiummetal. Because the lithium metal has a higher purity than lithium metalcurrently on the market, the lithium compounds or alloys produced usingthe high purity lithium desirably have a lower overall impurity level.

In an embodiment, the electrolytic cell can be a flow cell, a cell withbulk catholyte, or a stand-alone flow battery. The anolyte side of thecell operates in the same way as previous embodiments. A sulfuric acidsolution which dissociates lithium carbonate placing lithium ions intosolution and venting off CO₂ is the preferred anolyte system, but thealternatives previously proposed are also acceptable. The catholyte sideof the cell is a flow system or bulk fluid system which contains a 100%volatile electrolyte. Alternatively, LiOH can be the electrolyte so thatthe only non-volatile portion is the same LiOH produced. For the purposeof manufacturing lithium hydroxide monohydrate, a weak electrolyte ofsuch as ammonium hydroxide, NH₃(aq) (ammonia in water), or othersuitable electrolytes, such as LiOH solution, could be used. The systemcould be operated at atmospheric pressure below the boiling point of theNH₃(aq) electrolyte (27 degrees Celsius), or the sealed system couldhave pressure equalized and raised slightly on each side of the system(minimized pressure gradient across the lithium ion conductiveglass-ceramic (LiC-GC) membrane) to raise the boiling point of theNH₃(aq) solution. Other 100% volatile catholytes could be used. A 100%volatile catholyte with higher conductivity may be desirable.

If lithium hydroxide (LiOH) is used as the electrolyte, theconcentration of LiOH increases during processing as lithium isprocessed through the membrane. As the concentration of LiOH increasesand the solution pH increases, portions of the LiOH electrolyte can beperiodically bled off and dehydrated, being replaced by deionized waterto lower the pH of the solution back down to the desired operatingrange; a continuous control, maintaining a specific concentration in thecirculating catholyte, could also be used. In such cases, operatingtemperature can be raised (though remaining below the boiling point ofthe LiOH electrolyte) to increase conductivity of the LiC-GC membrane.

The conductivity of lithium ion conductive glass-ceramic (LiC-GC) plateis approximately 3×10⁻⁴ S/cm or 0.3 mS/cm at room temperature.Conductivity of a 5-10% NH₃(aq) solution is approximately 1115 mS/cm atroom temperature. Voltage applied to the cell results in migration oflithium ions across the membrane into the catholyte. The exact voltageversus Li⁺ ion flow rates through the lithium ion conductiveglass-ceramic (LiC-GC) plate need to be determined. If voltage is heldbelow the potential required to convert lithium ions into lithium metalthen the lithium ions would remain in solution in the catholyte. Whilenot wishing to be bound by theory, it is believed that if voltage israised until the current flows (which indicates Li-M production at thecathode), and then lowered until current is zero, Li⁺ is still passingthrough the lithium ion conductive glass-ceramic (LiC-GC) plate. If thevoltage required to provide an acceptable lithium transfer rate acrossthe membrane results in plating of lithium metal at the cathode then thelithium metal can be dissolved back into the catholyte by using ashutter over the lithium ion conductive glass-ceramic (LiC-GC) membrane.With the non-conductive (such as polypropylene) in place then thelithium metal should react with and dissolve into the catholytesolution.

The catholyte solution could then be converted into lithium hydroxidemonohydrate by either bulk processing of the bulk catholyte, or acontinuous distillation process for a flowing catholyte. For bulkprocessing, the bulk catholyte is transferred to a vacuum chamber wherethe catholyte is heated to drive off the volatile electrolyte, leavingbehind pure lithium metal or lithium hydroxide (when water is the finalcomponent to evaporate off). When NH₃(aq) is used as the catholyte, theNH₃ should evaporate off first and can be reclaimed in a condenser. Thewater is then evaporated off and reclaimed also. The result is lithiumhydroxide (anhydrous) or lithium hydroxide monohydrate depending on thelevel of drying.

By way of example and not limitation, the following examples areillustrative of various methods of producing the high purity lithiummetal of the present disclosure. The processes below are provided forexemplification only, and they can be modified by the skilled artisan tothe necessary extent, depending on the special features that aredesired.

EXAMPLES Example 1

The cell used for Example 1 is shown schematically in FIG. 4. The cell110 includes cell cover 116, retainer 118, platinum (Pt) anode 112,cathode 124 and a lithium ion conductive glass-ceramic (LiC-GC) 114 withlithium ion conductive barrier film 120 incorporated into a porouspolyolefin flat-film membrane 122. The supported lithium ion conductiveglass-ceramic-barrier film (LiC-GC-BF) multilayer is intercalatedbetween cathode 124 and a lithium ion-rich electrolyte 18 (as shown inFIGS. 1 and 2). The cell further comprises supporting Teflon® sleevestructure 126 with gaskets 128. One gasket seals between the lithium ionconductive glass-ceramic (LiC-GC) and the housing to prevent leakage ofthe electrolyte from the anode compartment into the cathode compartment.The other gasket allows for even compression of the lithium ionconductive glass-ceramic (LiC-GC) by the Teflon® sleeve to preventbreakage of the lithium ion conductive glass-ceramic (LiC-GC) plate.

The cell 110 includes anode 112 that is a platinized titanium anode,1″×4″ rhodium and palladium jewelry plating. The cathode is a palladiumcathode disc fabricated in-house, 1.4 inch round. The lithium ionconductive glass-ceramic (LiC-GC) 114 material is LICGC® G71-3 N33: DIA2 IN×150 μm tape cast, 150 μm thick, 2 inch round from OharaCorporation, 23141 Arroyo Vista, Rancho Santa Margarita, Calif. 92688.

The lithium ion conductive barrier film (Li—BF) 120 is fabricated from:a cyanoethyl polyvinyl alcohol (PVA-CN) polymer supplied by the UlsanNational Institute of Science and Technology in Ulsan South Korea, Dr.Hyun-Kon Song, procured from Alfa Aesar, stock number H61502; LiPF₆(lithium hexafluorophosphate), 98%; EMC (ethyl methyl carbonate), 99%,from Sigma Aldrich, product number 754935; EC (ethylene carbonate),anhydrous, from Sigma Aldrich, product number 676802; and a porousmembrane, ND420 polyolefin flat-film membrane from Asahi Corp.

The lithium ion conductive barrier film (Li—BF) 120 is fabricated in anargon purged glove bag. The glove bag is loaded with all materials,precision scale, syringes, and other cell components, then filled, andevacuated four times before the start of the electrolyte fabricationprocess.

The organogel electrolyte is mixed as follows: 4.0 ml of ethyl methylcarbonate (EMC) placed in a vial. Ethylene carbonate (EC) is liquefiedby heating to about 140° F. and 2.0 ml of the ethylene carbonate (EC) isthen added to the vial. 0.133 g (2% wt) cyanoethyl polyvinyl alcohol(PVA-CN) polymer is added to the vial and the mixture is agitated for 1hour to dissolve the cyanoethyl polyvinyl alcohol (PVA-CN). Then 0.133 g(2% wt) fluoroethylene carbonate (FEC) is added as solid electrolyteinterphase (SEI)-forming additive, and 0.972 g (1M) LiPF₆ is then addedand mixed to complete the organogel electrolyte mixture. Alternatively,the electrolyte can be a 1.0 M DMC-LiPF₆ solution of 15.2 g LiPF₆ in107.3 g dimethyl carbonate. The electrolytic cell is then assembledinside the glove bag. With the lithium ion conductive glass-ceramic(LiC-GC) and gaskets in place, the anode and cathode compartments aresealed from each other. The organogel electrolyte mixture is used to wetthe cathode side of the lithium ion conductive glass-ceramic (LiC-GC),the Hipore™ membrane is placed on the cathode side of the lithium ionconductive glass-ceramic (LiC-GC) and wetted again with organogelelectrolyte mixture. The cathode disc is then placed on top of theorganogel mixture. The cell is placed in a Mylar® bag and sealed whilestill under argon purge. The sealed Mylar® bag with assembled cell isthen placed in an oven at 60° C. for 24 hours to gel the electrolyte.

The electrolytic cell is removed from the oven and placed in the argonpurged glove bag, and allowed to cool to room temperature. Clear polyprotape is used to seal the empty space above the cathode disc and securethe electrode wire. The electrolytic cell is now ready for use, isremoved from the glove bag, and is connected to the electrolytecirculating system.

An electrolyte 18 is prepared with 120 g of lithium carbonate in 200 mlof deionized water and 500 ml of 20% wt sulfuric acid. The sulfuric acidis slowly added to the lithium carbonate suspension and mixed well.Undissolved lithium carbonate is allowed to settle. A supernatant iscollected from the stock solution, an 18% wt lithium stock solution. The18% wt lithium solution has a measured pH of 9. Solution pH is loweredby addition of 20% wt sulfuric acid. Again, the sulfuric acid is addedslowly to minimize foaming. The 18% wt lithium stock solution isadjusted to pH 4.5. Preferred pH is between pH 3.0 and pH 4.5, mostpreferred is between pH 3.0 and pH 4.0, but the process can be run at apH of 7.0 or below. A pH above 7.0 will result in carbonate in solution.

The electrolyte mixture is then poured into the circulating system. Thecirculating pump is primed and solution circulated for 30 minutes tocheck for leaks.

The lithium ion-rich electrolyte 18 flows through the top half of cell110 over the lithium ion conductive glass-ceramic-barrier film(LiC-GC-BF) multilayer 114/120 and past anode 112. When potential isapplied to the system, lithium metal builds up on the moving cathodebelow the lithium ion conductive glass-ceramic-barrier film (LiC-GC-BF)multilayer 114/120 system.

A Gamry Reference 3000 Potentiostat/Galvanostat/ZRA is attached to thecell 110. The pulse begins at 80 or 60 mAh for 2 seconds, then voltagesat approximately 3 V to approximately 3.6 V. At voltages of 3-6 voltsthere is no significant activity. When the voltage is raised to 10V, thesystem responds. Amperage draw increases when the voltage is raised to11 vdc. No gassing on the anode side of the cell was noted at 11 vdc.The Gamry Reference 3000 would not go above 11 vdc. Since no gassingoccurred at 11 vdc, the reduction rate could most likely be much higherif voltage were increased. An even higher voltage and reduction rate arepreferable if achieved with negligible oxygen production at the anode.The pH of the electrolyte at time zero is 4.46. The pH of the solutiondecreases to 4.29 after 35 minutes, and is 4.05 at the end of theexperiment. The lowering pH indicates lithium ion removal from theelectrolyte solution.

An amperage draw of 20 mA is noted at the start of the experiment. Theamperage draw slowly increases to 60 mA after 30 minutes. Amperage holdsfairly steady at this value for another 30 minutes. Experiment timer andgraph are paused for 30 minutes to extend experiment (voltage held at 11vdc). After approximately 65 minutes of run time, a large amperage spikeand sudden vigorous gassing is noted on the anode side of the cell. Thisis indicative of lithium ion conductive glass-ceramic-barrier film(LiC-GC-BF) 114/120 membrane failure.

Rapid gassing and bright white flame is observed when the cell 110 isopened and cathode 124 is exposed to electrolyte leaking through thelithium ion conductive glass-ceramic-barrier film (LiC-GC-BF) 114/120,evidencing that the cell produces lithium metal by electrolysis oflithium ions in a sulfuric acid aqueous solution, through a lithium ionconductive glass-ceramic-barrier film (LiC-GC-BF) 114/120 membranesystem.

Example 2

The cell used in Example 2 is shown schematically in FIG. 3D. The cellincludes sleeve 1, cell body 3, cathode 5, anode 9, lithium ionconductive glass-ceramic (LiC-GC) membrane 2 with lithium ion conductivecatholyte 10, lithium ion containing electrolyte 11, and O-ring 4 as aliquid seal between the two compartments. The supported lithium ionconductive glass-ceramic (LiC-GC) membrane 2 is intercalated betweenelectrolyte 11 and catholyte 10. The cell further comprises supportingcathode 5 in contact with the catholyte 10 during deposition and anode 9in the electrolyte 11. One O-ring 4 seals between the cell body andsleeve to prevent leakage of the electrolyte from the anode compartmentinto the cathode compartment.

The cell includes anode 9 that is compatible with strong sulfuric acid.A platinized titanium anode, 1″×4″ rhodium and palladium jewelry platingwas used in the test cell, however high over-potential anodes may not berequired as there is no electrical path for electrolysis of water on theanode side of the cell. The cathode used was a palladium cathode discfabricated in-house, 1.4 inch round; however this can be a differentmaterial compatible with the catholyte 10 and lithium metal. The lithiumion conductive glass-ceramic (LiC-GC) material is LICGC® G71-3 N33: DIA2 IN×150 μm tape cast, 150 μm thick, 2 inch round from OharaCorporation, 23141 Arroyo Vista, Rancho Santa Margarita, Calif. 92688.

Several electrolytes can be used for catholyte 10, including a simplelithium battery electrolyte such as lithium hexafluorophosphate solutionin ethylene carbonate and dimethyl carbonate (EC-DMC-LiPF₆), a mixtureof dimethyl carbonate and lithium hexafluorophosphate (DMC-LiPF₆),trifluoromethanesulfonyl-imide (TFSI) Ionic liquid based electrolytessuch as N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide(Pyr₁₄TFSI), or ether based electrolytes such as, 1,3-dioxolane(ethylene glycol methylene ether), sulfone based electrolytes such assulfones such as ethylmethylsulfone (EMS), methoxy-methylsulfone (MEMS)or tetramethylsulfone (TMS) are good candidates to produce lithium withsolid electrolyte interphase (SEI) layers specifically for electricvehicle batteries that operate at high voltages, or a more complexlithium ion conducting barrier film (Li—BF).

The electrolyte 11 is prepared with 120 g of lithium carbonate in 200 mlof deionized water and 500 ml of 20% wt sulfuric acid. The sulfuric acidis slowly added to the lithium carbonate suspension and mixed well.Undissolved lithium carbonate is allowed to settle. A supernatant iscollected from the stock solution, an 18% wt lithium stock solution. The18% wt lithium solution has a measured pH of 9. Solution pH is loweredby addition of 20% wt sulfuric acid. Again, the sulfuric acid is addedslowly to minimize foaming. The 18% wt lithium stock solution isadjusted to pH 4.5. Preferred pH is between pH 3.0 and pH 4.5, mostpreferred is between pH 3.0 and pH 4.0, but the process can be run at pH7.0 or below. A pH above 7.0 will result in carbonate in solution.

The electrolyte mixture is then poured into the circulating system. Thecirculating pump is primed and solution circulated for 30 minutes tocheck for leaks.

The lithium ion-rich electrolyte 11 flows through the bottom half ofcell body 3 over the lithium ion conductive glass-ceramic (LiC-GC)membrane 2 and past anode 9. When potential is applied to the system,lithium metal builds up on the cathode above the lithium ion conductiveglass-ceramic (LiC-GC) membrane.

A Gamry Reference 3000 Potentiostat/Galvanostat/ZRA is attached to thecathode 5 and anode 9. The pulse begins at 80 or 60 mAh for 2 seconds,then volts at approximately 3 V to approximately 3.6 V. At voltages of3-6 volts there is no significant activity. When the voltage is raisedto 10V, the system responds. Amperage draw increases when voltage israised to 11 vdc. No gassing on the anode side of the cell was noted at11 vdc.

FIGS. 3A-3E illustrate an insertion/retraction module-adapted cell thatincludes a cathode support that positions the cathode. The support canbe driven by a servo-motor or the like that transmits the cathode towardand away from forming lithium. A non-conductive sleeve 1 contains theliquid catholyte 10 and provides electrical insulation between the anodeand cathode compartments.

To produce lithium, a lithium ion-containing acid electrolyte isdirected through the anode side of the cell. The cathode side is filledwith a suitable anhydrous electrolyte, then a cathode is inserted intothe electrolyte, and potential is applied to initiate the electrolysisprocess. The cathode can be withdrawn, and formed lithium is harvestedright off the cathode and the cathode reinserted.

This method provides a fully scalable and cost-effective automatedproduction process. In one aspect, controls are built into the system tomonitor current draw to each cell. A sudden increase in current drawindicates water electrolysis due to failure of a lithium ion conductiveglass-ceramic (LiC-GC) membrane at which time the cathode can beretracted and that cell isolated from the acid electrolyte feed, othercells can continue production. The cell unit can then be changed out andproduction resumed on that cell.

Lithium carbonate is the process feed stock. Lithium carbonate having apurity as low as 90% may be used as the feed stock. The lithiumcarbonate is added to a sulfuric acid solution which releases CO₂ andplaces lithium ions into solution. Oxygen from the lithium carbonatereacts with the solution to neutralize hydronium ions or form hydroxylions (as noted by an increase in pH). Upon application of a potentialacross the electrolytic cell, lithium ions migrate through the lithiumion conductive glass-ceramic (LiC-GC) membrane and form lithium metal onthe cathode, while oxygen is produced at the anode by conversion ofhydroxyl ions or water back to hydronium ions (as noted by decrease inpH during electrolysis). According to the example, anode compartmentsand cathode compartments are decoupled electrically so that the onlyelectron flow is that of lithium ions through the lithium ion conductiveglass-ceramic (LiC-GC) membrane. Electrons are provided at the cathodeconvert lithium ions to lithium metal.

Electrons are given up at the anode from water or hydroxyl ions (OH⁻)that have been created during addition of lithium carbonate. Non-aqueouselectrolyte on the cathode side of the cell can be any suitable liquidor gel electrolyte. For example, a lithium hexafluorophosphate solutionin ethylene carbonate and dimethyl carbonate (EC-DMC-LiPF₆) mixture, ora lithium hexafluorophosphate solution in dimethyl carbonate (DMC-LiPF₆)mixture is suitable.

In the process of Example 2, a cathode is inserted into the cell at aspacing from the lithium ion conductive glass-ceramic (LiC-GC) membranethereby dispensing with the barrier layer that is required by otherprocesses. Cathode and anode compartments are not electrically coupledas proposed in other processes and instead are electrically isolated.Consequently, only lithium ion flows through the membrane. Electrolysisof water on the anode is prevented as is the associated parasiticelectrical losses from water electrolysis. This permits the use of ahigher voltage.

Electrolyte: H₂SO₄→2H⁺+SO₄ ²⁻

H₂SO₄→H⁺+HSO₄ ⁻HSO₄ ⁻→H⁺+SO₄ ²⁻

Feed stock reaction: 2Li₂CO₃+4H⁺+4Li⁺+2CO₂+2H₂O (reduces pH)

2Li₂CO₃+2H⁺→4Li⁺+2CO₂+2OH⁻(reduces pH)

Anode reaction: 2H₂O→4H⁺+O₂+4e ⁻

2OH⁻→2H⁺+O₂+2e ⁻

Cathode reaction: 4Li⁺(aq)+4e ⁻→4Li(s)

Net: 2Li₂CO₃+electricity→4Li(s)+2CO₂+O₂

2Li₂CO₃+electricity→4Li(s)+2CO₂+2OH⁻

Example 3

Lithium metal was obtained using the cell and process conditions ofExample 2, except that: stainless steel was used as anode, a copper discwas used as cathode, the cathode was stationary, and aninsertion/retraction module was not implemented.

The lithium metal formed on the cathode 5 was analyzed using aninductively coupled plasma mass spectrometry (ICP-MS) method.Specifically, the high purity lithium metal is ionized with inductivelycoupled plasma and then subjected to mass spectrometry to separate andquantify the ions in the high purity lithium metal. The results areshown in Table 1 below:

TABLE 1 Li 99.9921 at %, including phosphorus 99.9648 wt %, includingphosphorus 99.9997 wt % on metals basis (excluding phosphorus) B 0 Na 0Mg 2.37 ppm Al 0 P  781 ppm K 0 Ca 0 Cr 0 Mn 0 Fe  1.8 ppm Ni 0 Cu Nottested Zn  1.1 ppm Sr Not tested Ba Not tested

It is believed that the presence of phosphorus is due to the electrolyteLiPF₆ contained on the cathode side of the membrane. Notably, the extentof inclusion of phosphorous is limited to the film surface-thefilm-electrolyte interface. X-ray photoelectron spectroscopy (XPS)analysis confirmed the presence of phosphorous only on the film surface(up to 10 nm), with a more pure core of lithium metal below that depth.In an embodiment, post-processing steps can be included to removephosphorus.

The lithium metal does not contain any ions other than lithium,magnesium, phosphorus, iron and zinc when analyzed by the inductivelycoupled plasma mass spectrometry (ICP-MS) method. Specifically, thelithium metal does not contain any of the following impurities: mercury,boron, sodium, aluminum, potassium, calcium, chromium, manganese, andnickel.

As shown in Table 1, the lithium metal has a lithium purity of at least99.96 weight percent (including phosphorus), and at least 99.9997 weightpercent on a metals basis (excluding phosphorus). However, the inventorbelieves that the presence of iron was due to the use of a stainlesssteel container to transport samples and that the iron impurity istherefore a result of lab handling and not the actual content of thelithium metal sample. Furthermore, the inventor believes that thepresence of zinc and magnesium was due to errors resulting from the useof an air conditioner in the testing environment. Therefore, in anembodiment, the lithium metal may not contain any trace impurities. Theinventor also believes that the presence of phosphorus is due to the useof a catholyte containing LiPF₆ which forms the resulting solidelectrolyte interphase (SEI) layer. Therefore, in an embodiment, thelithium metal purity may be higher than 99.998 weight percent on ametals basis, and 100% using an electrolyte in catholyte 10 that doesnot form a solid electrolyte interphase (SEI) layer. These values candiffer (can be controlled) because only lithium ions enter catholyte 10,and a variety of electrolytes can be used in catholyte 10, which resultin the formation of an optimal solid electrolyte interphase (SEI) layer,or none at all.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A process of producing lithiumhydroxide comprising: extracting lithium metal from a lithium salt usinga selective lithium ion conducting layer; and processing the lithiummetal with deionized water to form lithium hydroxide and lithiumhydroxide monohydrate.
 2. An electrode comprising: lithium hydroxidemonohydrate, wherein the lithium hydroxide monohydrate is obtained by aprocess as recited in claim
 1. 3. A battery comprising: an electrodecontaining lithium hydroxide, wherein the lithium hydroxide is obtainedby a process as recited in claim
 1. 4. A battery comprising: anelectrode containing lithium hydroxide monohydrate, wherein the lithiumhydroxide monohydrate is obtained by a process as recited in claim
 1. 5.A battery comprising: an electrolyte containing lithium hydroxide,wherein the lithium hydroxide is obtained by a process as recited inclaim
 1. 6. A process for separating Lithium-6 and Lithium-7 isotopesfrom a lithium metal, the process comprising: providing an electrolyticcell comprising an organic aqueous solution, a nonaqueous electrolyteand a selective lithium ion conducting membrane, and causing theLithium-6 and Lithium-7 isotopes in the lithium metal to pass throughthe membrane at different velocities, and capturing at least one of theLithium-6 and Lithium-7 isotopes.
 7. The process of claim 6, wherein theprocess is run at least two times using an electrolyte selected from thegroup consisting of 18-crown-6, 2,2,2-cryptate, and polyethylene glycol.8. An enriched Lithium-6 isotope obtained from lithium metal by aprocess as recited in claim
 6. 9. The enriched Lithium-6 isotope ofclaim 8, wherein the process is run two times using an electrolyteselected from the group consisting of 18-crown-6, 2,2,2-cryptate, andpolyethylene glycol.
 10. An enriched Lithium-7 isotope obtained fromlithium metal by a process as recited in claim
 6. 11. The enrichedLithium-7 isotope of claim 10, wherein the process is run two timesusing an electrolyte selected from the group of 18-crown-6,2,2,2-cryptate, and polyethylene glycol.